There's also the fact that there are other potential incarnations of Kirby also wandering around the universe, except they're evil. Also they seem to be able to kill omnipotent gods somehow. And potentially create them too. I think there was also something about Nova or whatever his name was being made by the same species Kirby is?
Which, because they're all dead except Kirby and Metaknight implied that there's something capable of killing them, too, that we've never seen.

Also Kirby probably never killed 0. It would seem he can't die in fact. And he seems to be what happens when Kirby reincarnates as evil instead of good.
The final boss of Kirby Squeak Squad is implied to be an incarnation of 0. In Japan his name is even "Dark 0."

Kirby lore is basically "Lovecraft for Kids" if you ask me. Way simpler than traditional cosmic horror, but it has the same elements.

In the last game, Forgotten Land, Kirby fights against a god level dimension warping motherfucker who corrupted all the animals and steals souls for power. After being Kirb stomped, Fecto Elfilis creates a pocket dimension to escape to that contains all the souls and warped versions of the bosses. A pivotal part of the end boss build up is a wall of flesh/psychic material chases after you, the goopy mass swarming with the faces of those it's consumed.

This isnt even lore yet - it's gameplay. Kirby is also haunted by Meta Knight, space wizards from other dimensions, and so much more. It isn't hype to just talk about what's happening in the game.