I’m usually pretty particular about the sorts of traits that get assigned as humanity’s “special thing” in sci-fi settings, but I have to admit that I have a weakness for settings where the thing humanity is known for is something tiny and seemingly inconsequential that it wouldn’t normally occur to you to think of as a distinctive trait.
Like, maybe we have a reputation as a bunch of freaky nihilists because we’re the only species that naturally has the capacity to be amused by our own misfortune.
Alien: Why are you happy? You’ve been seriously injured!
Human: *struggling to control laughter* Yeah, but I can imagine what that must have looked like from the outside, and it’s pretty hilarious.
(I may or may not have been influenced by Buck Godot, where the thing humanity is known for is that we were the first species ever to think of freezing flavoured water and putting it on a stick. Earth is known throughout the galaxy as the Popsicle Planet.)