These are some small observations and theories. There are a ton of good ideas on this board and there are some really good theories. I dont want to try to try to figure out all of what is going on but i do want to list some things that i have noticed.
The most recent thing ive noticed is from a screen cap of Kate being #51 on the lighthouse wheel and that she is not crossed out. Im not sure what this means and i find it really strange. However, Littleton was on the cave (313) i think and was crossed out along with a bunch of other characters from the show. What if there are 2 sets of numbers? One for each mib and Jacob.
Regarding Flocke; He has shown a massive amount of desperation in the "Substitute". One of a few things could be developing here w Flocke. Lockes remnants could be surfaceing, he is starting to see the uphill battle infront of him, he has realized the loophole wasnt as awesome as he thought it would be, or there is inner conflict brewing inside of him.
I belive without a doubt that Jack Shepard is 23 and not Christian. Jack has throughout the series benn marked w #23. I dont believe that there has been anything linking Christian to #23 ever in the series. Christians will had Jacks x's address on it but i dont know if that means anything or not. I do believe that Jack will be the new Jacob as he was a man of science andwould now be a man of faith as locke was a faith baesd man a was taken by a scientific being. I wouldnt mind if it ended where Flocke tells Fjack how badly he wants to kill him just like the last episode of season 5.
Regarding the big picture; I really think that all of the ancient architectur is really a smoke screen to make you think that Jacob and MIB are from ancient times. I dont think they are from our planet. I think the island is a window to another place/time. All the civilizations who were brought therer built everything on the island not MIB and Jacob. The creators of this show once stated that the show will probably end "somewhere near the Milkyway Galaxy". I believe the smoke monster is an A.I of some sort and that Jacob may be as well. I think that they are computer progams sent to search the universe for inhabital/cross breeding beings worthy of the aliens who sent out the program. I know i just lost about everyone just then but i dont think the show is rooted in earths history at all. Maybe its not the human race that is at stake but something much larger.
I would like to thank everyone on this board for mkling this so enjoyable. There will never be anything like this for a long time. Peace to all.