I recently rewatched the first episode, and i would like restate something that im sure has been posted here before. I believe that Jacob take the form of Vincent. Vincent is the first entity in the show after Jack. Right after he wakes up we see Vincent come out of the jungle almost beckoning him with the ominous music. As Jack runs out of the forest there is a slow pan on his father's shoe in the trees representing the MIB who we assume Christian. I think these two figures are actually a sly introduction to the theme of the show, MIB and Jacob showing their presence on the island. Later in the episode (27:50 to be exact), there is a shot that shows Vincent panting and watching over Charlie Kate and Jack. The music and the length of the shot are what convince me, its just seems way to intentional of a hint. Its been rumoured that the producers said we have seen Jacob before the incident, and that he hasnt talked! . With a lot of people thinking this means he is Aaron, i think it eludes to Vincent. Also in an episode that was on scifi today, Vincent leads Shannon to Boones grave, when he is suppose to be finding Walt. I think its another case of Vincent (jacob) showing guidance. I mean why would she bring her there of all places. SO maybe Vincent died on the wreck and was possessed