I think religion probably got it's start by some well meaning parent as an inventive tale to help the kids deal with the death of a tribe member.
Then the laziest member of the tribe - deviously co-opted these stories to control the more gulliable tribe members for personal gain.
....
Thus the priesthood born....
Then the laziest member of the tribe - deviously co-opted these stories to control the more gulliable tribe members for personal gain.
....
Thus the priesthood born....