You dig deep with this one- these are some very thought-provoking points, @Garnet! 
Perhaps it’s a bit ironic that I’ve always loved studying different cultures but always struggled with history (art and traditions call to me, but dates and names vanish from my memory within minutes 
). But I agree- it is fascinating to realize how civilizations and empires have risen and fallen over the years- some fade, and others are merged or adapted into new eras.
There’s another discussion that ties into this well about the place of angels in Wicca and how many deities appear in different forms across different religions and cultures. Sometimes cultures do vanish- but othertimes they are adapted and survive in new forms through other cultures or the traditions that follow in their wake.
It’s a really interesting thing to consider- and certainly opens the door to more questions and exploration! Thanks for sharing your thoughts, Garnet! 