Hold off on condemning it just yet. The more I think about it, the more okay I am with it.
I think they want you to decide for yourself what all the rest was - why the island was there, what the smoke monster was about (They kind of explained that the smoke monster was a mistake on Jacob’s part, by killing his brother, he created it.) (And when Linus was given another chance in the temple, it was the Man In Black giving it to him).
You kind of have to suspend your disbelief with this show, now - just like watching Kink Kong, you have to accept that a giant ape lived on an island with no mates or other apes, with dinosaurs and giant insects, and not knowing how they got there.
I also suspect they may have left themselves a lot of material to go back to, if they ever decide to make another show, or a movie, or even books. The island could be eternal, and they could have endless sequels and prequels with it. Will they ever go back? Who knows?
“Kink Kong” indeed. Face it, the script is an incoherent mish-mosh.