Hey @charlie.wilson - are you familiar with the Book of Enoch? It was a part of the Dead Sea Scrolls collection along with several other Hellenistic era works. The first part of the book of Enoch parallels and describes a story in the book of Genesis where a group of "angels" bind themselves to an agreement to give mankind knowledge in exchange for copulating with human women. In Genesis they are referred to as Sons of God, whereas in Enoch they are referred to as the Watchers.

Although I can't say one way or another who exactly built the pyramids (my leaning it towards the first scenario - or perhaps even a combination of both). I think humans built the pyramids, but I think it is possible they (some in the ruling hierarchy) were given instruction or knowledge on how to do so by ET intelligence. Whether thats angels or aliens (or both) remains to be seen ;)