I'm familiar with the book of Enoch. I don't think it's legit. I believe the sons of God are men. The book of Enoch was likely written a few hundred years before Christ. It's also possible that Jude is quoting from some other document and that the Book of Enoch also quotes from that document. We don't know.
Genesis 6 clearly said those sons of God are divine beings. The biblical definition of son of God is either angel or a human being born again in the Spirit. In the time of Genesis no human being is yet born again in the Spirit.
The book of Job chapter 1 mentioned the term “sons of God” who came to present themselves before God along with Satan and it referred solely to angels.