An afterlife would be terrifying for me

[Belacqua]

Of course this is all guess work based on various prehistoric archaeological finds and how some of the dead were buried or other signs. No one knows for sure but it makes logical sense that prehistoric view of afterlife would be simple rather than complex.

I suppose which guesses seem logical depend on one's imaginings about those people. You may be right. 

Whether their fantasies had anything to do with later theories is a difficult question.

I don't know anything about Muslim theology. I don't know if the rivers of milk and honey are symbols for otherwise ineffable things or not. 

Certainly the views of the Christians I named are deeply philosophical, rooted in centuries of work about what happiness consists of, and how people lack this happiness.