Genesis 6 makes a whole lot more sense.
My Bible doesn’t either. Like a said earlier it is not an inspired book but provides an expanded history of all the stuff going on before the flood, thanks to the fallen angels. You will notice Genesis 6:12 says that the whole earth became corrupted. Also, it includes a lot of other things that Enoch experienced, and prophecies about the coming of the Son of Man. The Book of Enoch has a couple of later gnostic insertions in it which I don’t care about.
Kind of like the Book of Jasher, mentioned I believe 2 times in the OT, Joshua and Second Samuel. Not inspired but a history book from the creation until the death of Joshua.