Difference is, those people invented art, they didn't copy it without understanding what it is. Also, Midjourney and Stable Diffusion can draw shadows because

Difference is, those people invented art, they didn't copy it without understanding what it is. Also, Midjourney and Stable Diffusion can draw shadows because humans figured out how to do it first. Because humans are humans, and they eventually figured out how shadows work. They didn't need to be shown thousands of examples of correct shadows before learning how to do it.