Season 1 - They all crashed. All the characters we knew and loved the last 6 years DID NOT DIE HERE! I repeat, they did not die here.
Season 2 - Stuff happened
Season 3 - Stuff happened
Season 4 - Stuff happened
Season 5 - Stuff happened
Amongst this stuff, lots of people died!
Season 6 - Let's ignore the alt. universe.
More people died. At the end, the Hurley is the new Jacob, the new protector of the island. He may be there for thousands of years, but eventually he will die. Ben is his sidekick, the new Richard, he may be there for thousands of years, and eventually he will die. Desmond is with them, but Hurley will get him off the island, he is the new Jacob, he has powers. Eventually he will die.
Jack died (with Vincent, Matthew Fox's dog in real life, laying next to him, so **ing sad). Kate, Claire, Sawyer, Lapidus, Miles, and Richard all flew off the island. Let's assume they lived happily ever after, but eventually, they all died too. Everyone dies! That's life for ya, death and taxes are the only two sure things.
Now this is where the opening of Season 6 starts, once everyone is dead. They are all in purgatory. It all begins in the plane because this is where the most important part of their lives began, where they met the most important people they would ever meet, Oceanic Flight 815.
Problem though is, they are dead but not at peace. They all can't move on. They all miss each other. There are too many stones yet unturned. Too many sins not atoned for.
Charlie tried to kill himself, but he couldn't die, he was already dead! When he saw this, he then had a flash of what meant most to him while he was alive . . . Claire. He opens the door for Desmond, and Desmond opened the door for everyone else. Every person had to realize what they all had been through, the giant adventure. They had to see all the sacrifices they made, all the things they did, the HELL they went through, and they had to see it together. Jack was just the last one to figure it out in the afterlife.
Ben couldn't move on just yet. Having Hurley give him a thumbs up and Locke forgiving him wasn't enough. He killed his dad, he killed his daughter, he killed all of Dharmaville! He wasn't ready yet, he needed to atone.
Everyone else though, they were sitting in the church, much like passengers in the plane, and the two most important people, Jack and Locke, were in the front row, on a flight to their ultimate peace.
That was the tv show LOST! It was an adventure about a group of people who were alone, they had no one, they were dubbed a tremendous responsibility, and they were all LOST. In the end, after they saved the world, after they made sacrifices, they were all together in the end, no longer alone, no longer LOST.