Of all the cast members shown, only one, Walt, was stated to be alive off the island (since we don't know if Ajira plane made it home).
There are debates whether any of the characters survived a mid-air plane break up. There are theories about whether the characters were cloned, saved by angels, teleported to a supernatural place, souls in purgatory, or experimental lab rats in a mental maze.
Whatever the true purpose of the characters, this photograph is a metaphor for each character (and the collective group's) standing in the wreckage of their own personal lives. How could they have survived a plane crash when each of them barely survived in their own lives? All of them were broken, physically and/or emotionally. All there futures were suspect and dark to foreboding. In one way or another, they had all messed up something important in their lives. It was an irreversible action that has no second chance, except in death (as in Jack's reunion with his father in the sideways church). There was little hope of cleaning up the wreckage of their personal lives back home. They all were doomed to some form of misery. And misery loves company.
The wreckage, misery, loss of direction, drifting away from responsibility or change is what is the common thread amongst the main characters. The were all lost to the fates that troubled their personal lives. The only happiness they would truly find was in their after life reunion, which is a sad commentary on life itself.
