Other lifeforms in the universe being basically humans with a bright shade of paint thrown on them.
This is one of the reasons I love Farscape. Sure, there were lots of funny-paint funny-nose-ridges humanoids. And lots of Leatherclad Fascist Space Australians. But the production team genuinely tried to make alien-looking aliens right from the start despite their budget and technology limitations. And as their budget improved they seemed to put all the extra money right into the puppets and prosthetics.
Of course Farscape did do the "a white human man is most important entity in the universe" thing. But I also forgive Farscape for that because John Crichton sure as hell didn't want any of that attention, he wasn't aiming to be a hero, he just wanted to fly under the radar and go home.