One of the primary reasons God in the Old Testament demanded sacrifices of animals is to prove a point. Most pagan religions, particularly the Egyptian one, either revered animals or were part animal in their visualization of their demon gods.
Christians will slaughter every cow in India one day and have beef tacos when they convert from demon worship.
In my belief system, the Eloha whom we call "Lucifer" and his scientific team were exiled here and not allowed to return to their home planet because they were revealing information to the Earthlings that was meant to be classified + fucking the human girls. They were violating some serious protocol.
So, while here, they were susceptible to Earth parasites and needed to have their bacon extra crispy to avoid getting sick. You may think my belief system is ridiculous, but I can't think of a better explanation for a "God demanding burnt offerings."
https://www.rael.org
Your belief system is also, pretty much, from the Book of Enoch. Have you ever read it?
I've only read commentary, but yes, would love to read the whole thing.
See chapters 6-8 - https://www.bibleword.org/wp/Enoch.pdf
"the Watchers" I believe were angels, but they could, I suppose, have been alien beings that breed with women and provided the basics of scientific knowledge.