More fuel for the ‘humans are the weird ones’ fire: We are arbitrarily frightened of creatures which can’t possibly hope to hurt us.
When a human crewmate begins howling fearfully after a routine stop on Terra, designated guards can’t get there fast enough. What sort of horrifying beast capable of frightening the all-consuming, self-poisoning, oxygen-breathing HUMAN could have possibly made it past security protocols?!
And it turns out it’s a cricket.
“Is it venomous?! Is it flesh-eating?! Does it spray some sort of biological agent that eats away at your neural pathways?!”
“No, it’s just CREEPY! It landed ON MY NECK!! Someone get rid of it!!”
Once the aliens understand the phenomenon of 'creepy’, they’re even more confused. What makes it creepy? Why, in its innocence of living, does the lowly cricket inspire fear? It’s so underdeveloped by Terran standards; it doesn’t even have the mental complexity needed to experience pain!
And let’s not forget that these fears aren’t universal. Some of us are not only indifferent to the presence of 'creepy’ animals, we actively seek to surround ourselves with them.
“Human-Jacob, why do you seek the assistance of Human-Vanessa when you find a Terran snake? Can you not hunt it yourself?”
“Oh, hell no. I’m not touching those things.”
“Is Human-Vanessa a predatory subspecies? Is that what enables her to capture them more efficiently?”
“What? No. She just thinks they’re cute.”