Re. timelines...

Several years ago I learned about the philosophical concept of "possible worlds" as the basis for "middle knowledge", a theory on how God can predict the future without causing it.

It's like a chess game: with each move, the set of remaining possible moves changes. The expert player will indeed win the game, but the path to that end may change many times. However, as the end of the game approaches, the set of possible moves dwindles to very few until there are no moves left at all.

This, IMHO, explains both the inexorable march to a predetermined end, and the changes people perceive along the way. This would also explain failed prophecies to some extent, though I also hold that most of them are just pulled from people's wishes or delusions.