Jeremy Jones explains the Lost finale
Sorta.
So, we have to begin with the idea from philosophy (because Lost is a show with many references to philosophy, not least of them being a prime character named "Locke" who Jack himself states was "always right") that reality, or any reality, even ours, exists simply as a mental construct that continues to exist only so long as we collectively believe in it. We make it. And only through the continued interaction with other wills/people who also believe in that reality does it persist. When you stop believing in that reality, you lose grip on it. You become "lost."
Alright, so, everything that ever happened on Lost that wasn't in the "flash-sideways" ACTUALLY happened. All of it. The island, the time travel, all the crazy stuff. Then Jack died after saving the island and Hurley became the new protector with Ben as his second in command. And someday, every one of them died. But we as the viewer stay with Jack, because he's the one who's most "lost" of them all.
See, the "flash-sideways" world was a reality created and persisting only on account of the continued belief of everyone from the island and their strong, unyielding desire to be together again. After each of them passed on, they all ended up in this shared reality where they're all kinda doing the things they'd always thought they wished to do. Desmond finally has the approval of Charles Widmore. Sawyer is living a more righteous life. Jack is a doctor still. Locke is getting married to his lady and has a father who's actually in his life, although a vegetable. See, they didn't get it all totally right, because the dead/lost souls are usually a little confused. This is a persistent idea in lots of mythologies that when souls are encountered in varied versions of the afterlife they tend to get the details of their lives mixed up.
So they're all "lost" in this reality until they are reminded, through various encounters, of who they'd been in life, and this is when they stop being "lost" and reunite with all the people they love. I.e. Jack's subconscious will might've thought what he really wanted in life was to be a doctor and a father and married to Juliette, but it's only once he's reminded of who he was that he remembers that he really loves and wants to be with Kate and, as Locke points out, has no son.
And in the end, they all come together in a Unitarian church, and all the concepts and imagery they play with here aren't inherently Christian, so people can stop bitching about that. They're pretty universally shared beliefs among multiple religions. Jack's dad tells him that everyone dies, some of them before him, some of them after. That's why Hurley tells Ben outside the church, "Hey man, you were a good second in command." Because they went on to protect the island after Jack died and one day also died and joined everyone in the "new reality" their collective will made.
Once everyone has been reunited and is no longer "lost" they're all ready to move on, finally. There's no indication as to what that means because the creators didn't want to be so bold as to say what happens when we all die.
In short, everything that happened was real, except the "flash sideways." The flash sideways was the slightly confused creation of the collective will of everyone to be together again after they'd died. Jack was the most lost, the most stubborn, and the last to accept it as always, and that's why we the audience follow him primarily. All the other questions about how the Dharma Initiative found the island, where the polar bear in the desert came from, and all that are completely irrelevant because in the end the show was really about this group of people and how the most important thing in all their lives was eachother. And it was only when they realized this themselves that they stopped being "Lost." And thus did "Lost" come to an end.
What about the last shot of Vincent coming up to lick Jack as he watched the plane fly overhead?
Vincent was still alive when Jack died. So were Rose and Whatsisface. They died later on, just like Hugo and Ben died much later on. As Christian said, "Some of them died before, some of them after."
Why was Penny there with Desmond? Why wasn't Locke's fiancee there?
Penny was there because she died some day, too, but she'd shared that experience with the group and she was Desmond's "Constant," so of course she'd end up there, too. As for Locke's fiancee, maybe she just wasn't connected enough to the group and connected only to Locke, directly, but it's arguable that she hadn't made nearly as big an impact on Locke's life as the group had. Also, it's entirely possible that actress Katey Sagal just wasn't available.
Why did it all have to end all Christian-y?!
It didn't. It ended in an ambiguously spiritual way.
But they didn't explain how the Dharma Initiative found the island! Or what was up with all the demigod stuff! Or etc, etc
Because that was never the focus of the show. The focus of the show was always these people, and the bonds between them, and how those bonds can be stronger than timelines, demigods, and even death. And I think that's a plenty fine message for the whole thing to end on.
So, we have to begin with the idea from philosophy (because Lost is a show with many references to philosophy, not least of them being a prime character named "Locke" who Jack himself states was "always right") that reality, or any reality, even ours, exists simply as a mental construct that continues to exist only so long as we collectively believe in it. We make it. And only through the continued interaction with other wills/people who also believe in that reality does it persist. When you stop believing in that reality, you lose grip on it. You become "lost."
Alright, so, everything that ever happened on Lost that wasn't in the "flash-sideways" ACTUALLY happened. All of it. The island, the time travel, all the crazy stuff. Then Jack died after saving the island and Hurley became the new protector with Ben as his second in command. And someday, every one of them died. But we as the viewer stay with Jack, because he's the one who's most "lost" of them all.
See, the "flash-sideways" world was a reality created and persisting only on account of the continued belief of everyone from the island and their strong, unyielding desire to be together again. After each of them passed on, they all ended up in this shared reality where they're all kinda doing the things they'd always thought they wished to do. Desmond finally has the approval of Charles Widmore. Sawyer is living a more righteous life. Jack is a doctor still. Locke is getting married to his lady and has a father who's actually in his life, although a vegetable. See, they didn't get it all totally right, because the dead/lost souls are usually a little confused. This is a persistent idea in lots of mythologies that when souls are encountered in varied versions of the afterlife they tend to get the details of their lives mixed up.
So they're all "lost" in this reality until they are reminded, through various encounters, of who they'd been in life, and this is when they stop being "lost" and reunite with all the people they love. I.e. Jack's subconscious will might've thought what he really wanted in life was to be a doctor and a father and married to Juliette, but it's only once he's reminded of who he was that he remembers that he really loves and wants to be with Kate and, as Locke points out, has no son.
And in the end, they all come together in a Unitarian church, and all the concepts and imagery they play with here aren't inherently Christian, so people can stop bitching about that. They're pretty universally shared beliefs among multiple religions. Jack's dad tells him that everyone dies, some of them before him, some of them after. That's why Hurley tells Ben outside the church, "Hey man, you were a good second in command." Because they went on to protect the island after Jack died and one day also died and joined everyone in the "new reality" their collective will made.
Once everyone has been reunited and is no longer "lost" they're all ready to move on, finally. There's no indication as to what that means because the creators didn't want to be so bold as to say what happens when we all die.
In short, everything that happened was real, except the "flash sideways." The flash sideways was the slightly confused creation of the collective will of everyone to be together again after they'd died. Jack was the most lost, the most stubborn, and the last to accept it as always, and that's why we the audience follow him primarily. All the other questions about how the Dharma Initiative found the island, where the polar bear in the desert came from, and all that are completely irrelevant because in the end the show was really about this group of people and how the most important thing in all their lives was eachother. And it was only when they realized this themselves that they stopped being "Lost." And thus did "Lost" come to an end.
What about the last shot of Vincent coming up to lick Jack as he watched the plane fly overhead?
Vincent was still alive when Jack died. So were Rose and Whatsisface. They died later on, just like Hugo and Ben died much later on. As Christian said, "Some of them died before, some of them after."
Why was Penny there with Desmond? Why wasn't Locke's fiancee there?
Penny was there because she died some day, too, but she'd shared that experience with the group and she was Desmond's "Constant," so of course she'd end up there, too. As for Locke's fiancee, maybe she just wasn't connected enough to the group and connected only to Locke, directly, but it's arguable that she hadn't made nearly as big an impact on Locke's life as the group had. Also, it's entirely possible that actress Katey Sagal just wasn't available.
Why did it all have to end all Christian-y?!
It didn't. It ended in an ambiguously spiritual way.
But they didn't explain how the Dharma Initiative found the island! Or what was up with all the demigod stuff! Or etc, etc
Because that was never the focus of the show. The focus of the show was always these people, and the bonds between them, and how those bonds can be stronger than timelines, demigods, and even death. And I think that's a plenty fine message for the whole thing to end on.