我都覺得應該冇咁兒戲既!  而 time travel 故事有度好，可以 flashback/flashforward 咁玩

I am not sure about this....but as i remember Oceanic 815 crahsed to the island because of some kind of energy explore....Am i correct?

yes ar.

yea yea      

like that man said in the beginning of episode 16: Jacob wants to prove him wrong on something.  Seems like Oceanic 815 is only one of Jacob's "experiments".  He has brought different people to the island before

And like the man said, they come, they fight, they destroy, they corrupt, and these just happen over and over again.  But Jacob does not think so, that's why he kept bringing different people to the island.  Oceanic 815 is one of them.  (that's my guess only)