If we are to believe the past life theory, humans should evolve though the incarnations, not de-evolve, because there are some who are worse than animals.
Dejavu is only a lag of an eye and a dis balance between a processing speed of a brain and slow-mo of a human eyeball.
The biblical stories are a re-writes of previous either holy scripts, stories or myths, but there are many proofs that a human kind existed in much developed civilization prior our written history, so it could be it.
There are no delusional things out there, just the ones which are not studied or explained. Even the biggest of oddities have a solid explanation.

You tagged #neoxian , so I am inviting you to join Neoxian.City Discord server, if you haven't already.