If you're a space-travelling human-like species, Ceres is pretty hospitable. Lots of water, lots of rock, enough gravity to keep things down while still being e

If you're a space-travelling human-like species, Ceres is pretty hospitable. Lots of water, lots of rock, enough gravity to keep things down while still being easy to get off of, a manageable temperature, and it's in the asteroid belt so there's plenty of nearby materiel for development (not to mention Jupiter not far away, energetically). Earth's too hot, too far away from anywhere, and at the bottom of a great big hole. The only reason we like it is because we've adapted to its environment. It's not very good real estate. Plus, it's contaminated with life, which means lots of big, complex, wriggly molecules that get everywhere and fiddle with things. Get those in your life system and the alien equivalent of anaphylactic shock is probably getting off lightly.