LOL. What is such a big deal about the Oceanic 6 that that Jacob went to such great lengths to get them back to the Island? How about they are all re-incarnations of people from an earlier time (Egyptian maybe) and that their presence is required at a precise point in time to vanquish Jacob's Nemesis.... his final words "They're coming"
Also.. remember Jacob (I think it was actually Jacob's mate) testing the young Locke for special powers and going away disappointed? Locke is now dead and presumably has just been a pawn in a bigger game or conflict. The remark - "Someday I'll find a loophole" (to kill you) indicates a conflict being played out by a strict set of rules.
Yup there are definitely strict rules. I suspect the 6 are required, as Jacob's move has to be one which "shows the best of Humanity". Perhaps people who have been bad, but can change. Or people who will sacrifice all, for the love of others.
I ultimately think Hurley will be "The Candidate", and he will be sacrificed to ensure the winner of said game, is Jacob (he can still win, even though he is dead - his rival simply has to be proven wrong). Remember the conversation at the beginning.
They are clearly arguing over the behaviour of humans. Why is it important, I don't know. It is this question that makes me think Aliens, I suspect Aliens want to either keep us in check at the very least, (Jacob), or destroy us before we are technilogically advanced enough to risk other worlds due to our "unstable" human emotions (BLack shirt).
The convo:
BLACK SHIRT:
Still trying to prove me wrong, arent you?
JACOB:
You are wrong.
BLACK SHIRT:
Am I? They come. They fight. They destroy. They corrupt. It always ends the same.
JACOB:
It only ends once. Anything that happens before that is just progress.
Sounds like Jacob is saying, let them be. They are simply growing as a race, and are going in the right direction. Black shirt has no such feelings, and sees us as a destructive who should NOT be trusted.
Here is another theory.
Jacob and Black Shirt are from another world, thousands of years in the future. We KNOW that Time Travel plays a BIG part.
Perhaps in this future, Humanity has learned space travel / whatever other scary powerful technology, and has waged war with Jacob and Black Shirts world. Perhaps in an effort to stop this war, or at least *win it*, they have come back in time, and are manipulating events to either gain the other hand, or change the course of humanity to ensure we do not get to the level where we can pose a threat.
Who knows, it is AWESOME fun theorising though
Gary.