The protagonist is a sixteen-year-old boy who was suffering from a terminal illness when he fused with a Metatron seed (a special type of blessing forged by the archangels). In addition to superior adaptation, he can copy skills and attributes, absorb matter and energy, as well as be semi-spiritual.

Polymorph Mutant: It's like Rimuru Tempest combined with Alex Mercer, but it's a mutant, which means it has a human form from the beginning. Well, combine Rimuru's powers at the beginning with the protagonist's powers that I mentioned above to get an idea of what I'm talking about.

I'm also thinking about it generating symbiotes, which, when entering the body of an ally, allow a psychic link and allow them to copy each other's powers, the same can be done between symbiote users.

Orgamech/Magimites: basically it would be a techno-organic version of the Polymorph Mutant.

He would become an orgamech being when nanites used for his treatment fuse with him when the protagonist's powers awaken for the first time.

Polymorh mutant