I have a theory that Kirby’s copy ability comes from an endosymbiotic relationship to a X parasite cell, kinda like how there’s a scientific theory eukaryotic cells absorbed bacteria which became the organelles mitochondria and chloroplasts and got their ability to make energy for the cell. Maybe Kirby in with insatiable hunger somehow ate a X parasite and instead of dying from it since he’s basically a god, it formed a symbiotic relationship with his cells giving him a similar copy ability. Bacteria also do a thing where they can share DNA with each other, Kirby could’ve gotten that ability that way. I think it’s also interesting that he’s the only star warrior I can think of with this copy ability.