I feel like this plot would actually really go well as a comedy. And instead of being left as a shell of himself, outlivng the stars, with no hope or sign of improvement, etc. etc. (very depressing), he could have some kind of gimmicky "hope" -- such as maybe he got a mortal pregnant and ended up with a giant killer baby and had to train it. So the two of them manage to nurse the galaxy back to health over eons. And they use their superpowers of calamity and unintentional destruction to do so.

So things are going well, but it's kinda boring.

He's fiddling with clay and comes up with all these bizarre creatures: one is tall, walks on four legs, and has brown spots and a long tongue that pulls leaves off trees. Another is slow, furry, hangs from branches, sleeps 20 hours a day, eats from twigs. Another lives in the ocean, glows in the dark, is shaped like a bell, flows like jelly, has long tendrils dangling from it, and is poisonous to the touch.

He somehow figures out how to create hoomans out of the same clay. And there's this tree with crazy good fruit on it, and a strange serpent that roams around kinda bored and manipulative. He gets the pretty one to eat the fruit. The hoomans figure out how to make babies, and the human race is born!

So the superhero doesn't feel like a complete failure. At least he managed to create something of a humanity he can be semi-proud of.