some cool mythical gems power system

sort of like a combination of devil fruits and what i *think* bleach's sort of "oh ichigo goes hollow" thing
based on the concept of like, mythological creatures have a connection to the Earth itself, so their hearts are gemstones, and they contain their soul. when these gemstones are infused into an object, the power of the creature is permanently imbued into it
humans, being humans, learned this shit and slaughtered a lot of mythological creatures to make tons of these soul stones or spirit stones or myth stones or w/e, and now mythological creatures barely even exist

there was one human, some kind of queen, that became so legendary that her soul split itself and inhabits these gem things. when another human eats one of these queen gem things, due to being another human, they attain amazing power. supposedly, if a mythological creature eats a mythstone of the same type of creature as they do, they, too, attain such power - the power to become something like a god, and have full control over your body. basically becoming truly immortal, and able to do weird shit, like flip your hands around or move your armbones into your legs to make yourself super fucking tall while having no arms.

normally the gems are placed into objects, but some people eat these gems, instead. such beings are usually called like "carnivores", because when they do that shit, they literally just eat someone's soul. there's a big struggle for dominance as the two personalities try to fight it - most of the time, carnivores will just essentially "resurrect" the creature they at the gem of, but in the body of a human. a human with lots of their magical powers, but still a human nonetheless. however, if they do succeed, then they become the equivalent of a demigod - not the same shit as one of those enlightened contortionist fuckers, but having practically unlimited magical power.

protagonist is either some kind of mythological creature that is hiding from the world, or is a human that ate a queen mythstone