Your insistence on using the word "nobody" there is an absolute without evidence. You underestimate the visualization capabilities of savants. For my 3D game

Your insistence on using the word "nobody" there is an absolute without evidence. You underestimate the visualization capabilities of savants. For my 3D game prototype, I created all of the meshes programmatically and wrote *and debugged* a mesh-slicing algorithm using only visualization in my own mind. Mostly I did indeed use primitives like spheres, cones, and boxes. Granted, huge caveats - I never finished a game from the prototype, and the meshes involved weren't that complicated; I was modeling imaginary robots not people. It's painful for me to use GUI or CAD tools because they're so much slower and less capable than the Dall-E image generator/CAD modeler/Star Trek Holodeck I have inside my own brain. This is in some ways limiting, analogous to a mathematician refusing to learn to use a computer. Nevertheless back to your point, I'm fairly certain I could model a plausible human programmatically from geometry primitives, but I won't claim to until I try. However what I am certain of is somebody can.