I think you're going way, waaaay far beyond the evidence to suggest that these farmers though Gagarin was a space alien. That's a funny little narrative, but I don't think it's remotely necessary.
These remote Soviet people weren't likely any stupider than you or me... Less educated, sure--but they knew what human beings looked like, and were aware of the fact that airplanes existed. This was more than a decade after WWII ended, after all.
I can think of a hundred perfectly terrestrial reasons why these isolated, remote farmers would have good reason to be apprehensive in this situation... I'd imagine they get almost zero visitors, so the sight of any strangers would probably be the big news of the year--let alone a military aviator parachuting down in bright orange clothes.
In fairness, I should confess that I'm pointing this out because it kinda bugs me for us to be looking down on these folks, as if they're children or simpletons. At the very least, that narrative seems to serve our own egos, more so than any interest in accuracy.