Remathilis
Legend
Even simpler:Mundane - Normal, realistic, possible in reality to some degree.
Extraordinary - Peak, limits of humanity, or skill that appears outside the bounds on possible. Feats of Strength, Dexterity, Math. There are examples here in reality.
Supernatural - Spirit, Myth, Power of Nature. The Divine.
Magic - "Weave", the fabric of reality that can be unwoven, tugged at, changed, or channeled.
Any issues with those definitions?
Mundane is stuff that exists in the real world, with typical assumptions of biology, chemistry and physics. You and I and all realistic fiction exists here.
Extraordinary is stuff that borders on the edge of reality, either by being extremely unlikely or outright impossible, but still gives the appearance of existing within a world of mundane reality. Action moves street level superheroes and hard sci-fi exist here.
Supernatural is when things outright break the rules of reality, but in ways that aren't well explained or handwaved. An owlbear or a dragon cannot exist biologically, zombies can't exist, and time travel is theoretically impossible. Superheroes, horror movies, and most sci-fi exist here.
Magical assumes a world where the supernatural is explained by its own internal rules and may or may not be accepted as existing. The Force is a known effect with specific rules. The wizarding world exists even if muggles don't know in it. D&D magic is so common it's a buyable commodity.
I think the separation lines aren't based on sources but by how far it deviates from reality.