The Bible isn't a book. It's a library. Literally.
The books you mentioned have been, to use a modern term, debunked nearly immediately at the time they were first introduced. There have been volumes written about each of them as to why they do not fit with what is included.
Gnosticism is annoying to me in it's universalism and it's utter uselessness. It all boils down to "I'm special because I have gnosis about X/Y/Z."
There's no real path to redemption or anything that heals. I'd rather try my darnedest to walk the straight and narrow path with Jesus as my guide than fiddle fart around with gnostic revelations through various means that always lead back to self-importance and pride, the original sin.