So are automobiles. To have a broken arm set by a physician is unnatural. To let it heal spontaneously would be natural, even if debilitating for life. Getting a medical degree is unnatural. Foraging and experimenting by trial and error would be natural, even if often lethal.
Children born with no brains or other monstrous deformities are natural.
Brain surgery to remove a tumor is unnatural. Anything supernatural is unnatural but is usually considered to be good by those who believe in the supernatural. Reading and writing are unnatural. Urinating whenever one has the urge is natural, but uncivilized. LSD is unnatural, though mescaline is natural.