Very interesting and worthwhile, but I don't believe the main claims have been properly proven.

Regarding The Book of the Watchers, the original wrote:

It’s the first time in Judeo-Christian thought that we get the idea of demons living in something that sounds a lot like hell.

I am very skeptical of the use of Judeo-Christian there. Incidentally, the article seems to be pulling a sleight-of-hand by not explaining the context of that book:

https://en.wikipedia.org/wiki/Book_of_Enoch

The original also wrote:

In the Gospels, Lucifer is promoted from cameo to main character.

The Gospels do not mention "Lucifer" in the original Greek. Several years of Gospel study have convinced me that Jesus did not believe in a personal Devil. It is quite possible Saint Paul did believe in the Devil as a person, because Saint Paul seemed to introduce a lot of ideas that had nothing to do with Jesus and a lot to do with Zarathustra.