I've yet to find a better rationale of the alien presence than the writings of the Nag Hammadi texts. I think it's worthwhile referring to these in the event of unexpected visitors or rather a more material manifestation of their presence.
Technically we can go back further in history to the Sumerian Cuneiform tablets but unlike the Gnostic texts the tablets are the word of the 'Gods who from heaven to earth came'.
That's Gods/Elohim plural (check that in Genesis for yourself) and is a big difference from mystic humans who warned us of mind parasites and inorganic beings from space manipulating our planet unseen. It's clear they've done nothing for us since Mesopotamia.
I'd rather be hunter gatherer than have anything to do with them. Far more honourable and in harmony with nature. John Lash explains why we should be serious about these Gnostic Samizdat texts the Vatican Church did its best to destroy.