I totally agree that Jacob and MIB are Aaron and Charlie Hume from the future. As far as how they ended up back on the island, no idea. It is plausible however that they went in search of their parents.
Concerning the end of the show and what exactly it is that Jacob and MIB are doing there on the island, why they don't age ect... I think obviously that they traveled into the past, way back into the past and for some reason don't age as a result of this. There's a theory out there about how if someone's fate determines that they'll die in 2010 and if they travel back in time say... a hundred years, then they will someone how manage to survive until 2010, even if it means living over a hundred years because that person's death isn't fated to happen until 2010. This theory has been used to explain why Richard doesn't age. I don't completely buy into it, but it is possible.
Anyways, I think Jacob and MIB are stuck in a causal loop, just like the compass Richard gave Locke....or did Locke give Richard the compass? hehe exactly. Basically, no matter what they do, it seems as though they are powerless to prevent they're younger, future selves from getting stuck in this causal loop. The world keeps repeating itself from they're perspective. Perhaps they retain their conciousness and memories from each iteration. I think MIB blames Jacob for this, and has a base desire to avenge his plight by killing him. Jacob though, I believe he shares a bit of Jack's stubborness and is detemined, despite however many set backs, that it is possible to change one's fate, to break the casual loop.
This, I think, fits in with some theories about the smoke monster being the guardian of fate, course correcting what has been wrongly changed.
Concerning the end of the show and what exactly it is that Jacob and MIB are doing there on the island, why they don't age ect... I think obviously that they traveled into the past, way back into the past and for some reason don't age as a result of this. There's a theory out there about how if someone's fate determines that they'll die in 2010 and if they travel back in time say... a hundred years, then they will someone how manage to survive until 2010, even if it means living over a hundred years because that person's death isn't fated to happen until 2010. This theory has been used to explain why Richard doesn't age. I don't completely buy into it, but it is possible.
Anyways, I think Jacob and MIB are stuck in a causal loop, just like the compass Richard gave Locke....or did Locke give Richard the compass? hehe exactly. Basically, no matter what they do, it seems as though they are powerless to prevent they're younger, future selves from getting stuck in this causal loop. The world keeps repeating itself from they're perspective. Perhaps they retain their conciousness and memories from each iteration. I think MIB blames Jacob for this, and has a base desire to avenge his plight by killing him. Jacob though, I believe he shares a bit of Jack's stubborness and is detemined, despite however many set backs, that it is possible to change one's fate, to break the casual loop.
This, I think, fits in with some theories about the smoke monster being the guardian of fate, course correcting what has been wrongly changed.