This is silly.
Here's a novel idea - maybe those ancient writers were
liars or
delusional!
Just because someone wrote some story a long time ago it doesn't mean it's true. Geez. Crackpots exist everywhere and at all times in history.
What if future civilizations uncover the writings of Marshall Applewhite (Heaven's Gate Cult) who believed that Hale-Bopp, an unusually bright comet, was the sign that humans were supposed to shed their earthly bodies (or "containers") and join a spacecraft traveling behind the comet that would take them to a higher plane of existence. In preparation Applewhite and others had voluntarily castrated themselves. And, at the appropriate time, all the members committed suicide.
Someone in the future is gonna read Applewhite's writings and believe we were visited by castrating space aliens.