Equally, you and I can't prove that hindu myth isn't a record of contact with advanced space aliens, and wouldn't it have been fun if it was.

But it's implausible for all kinds of basic reasons.

It's just clear all throughout history that humans do not have trouble making up fantastic creatures. There's no reason to think that these fantastic creatures weren't made up. It just seems at first blush that there might be a reason because it was "very long ago." Until you realize that "very long ago" by the standards of hindu myth are wildly different than "very long ago" by the standards of hominid species.