And so a sensible person seeks (perhaps justifiably) prosaic explanations for everything and automatically excludes any hypothesis without a prosaic explanation (with the incredibly audacious conceit of assuming we already understand enough about the universe to make such assumptions), while the fantastical person, not as bound by the need for evidence, can wildly speculate (which would of course include nonhuman intelligences somehow visiting us over distances that are insurmountable to us currently, but might also include basically, well, anything, since without the hard-evidence requirement, you're free to get creative)

I think both of these points exist as extremes on a continuum and that they're both wrong in some capacity. I think pragmatism and reasoning and rationality are a good basis, however... just, limiting, as well.

We might advance a bit on the evidence front here if there was a scientific way to evaluate mass eyewitness testimony (individual eyewitness testimony has come under fire recently https://www.scientificamerican.com/article/do-the-eyes-have-..., but perhaps, if you multiply the number of witnesses, the errors will tend to cancel each other out and you might end up with something more like Evidence with a capital E. (This would be useful in far more areas than mere UFO observation, of course.)