John's Immortality

Well.. Think of the odds of mankind existing in the first place (or even advanced life on earth in general), all of the things that had to happen to lead up to it. If an alien race made a movie about a strange distant planet where the perfect storm of events led to evolved primates creating the ipad, I would imagine they would have some viewers questioning that likely-hood.

It's a movie where suspension of disbelief (like with most movies) is necessary, although they did cleverly touch on most of those concerns with John's dialogue (how he migrated, what professions he took up etc, all would have kept him out of much of the troubles of those eras). With the one time where he decided to put himself in the middle of things and try to make a difference he was crucified and came very close to death.

They eluded to the fact that there were possibly others like him, many of which likely perished throughout time. All part of the narrative they were creating where it was all very unlikely but none of them could actually disprove him.

I would think a lot of things would hamper him that soft tissue regeneration doesn't fix. Do his teeth regrow, because accidents aside the would have worn away ages ago. How much lead/mercury/etc has accumulated in his blood?

Not sure but it seems with that much time and he mentioned he had many sicknesses over the years but the never died it could likely mean he can't die by conventional means.

What would be interesting is something that happens to him that he can't change but he also can't die. For exampe, if someone chained him up and threw him into a deep ocean, he would just keep drowning. Or being dropped into a huge cave that then has a cave in so he gets buried alive, can't move at all so even with thousands of years on his hands he wouldn't be able to move even a few sand corns. Watching that kind of fate wouldn't be annoying or wouldn't make much of a movie but it's still an interesting concept.