The only reason it’s being treated differently from the television-camera example that I offered above is because the process of displaying it in the game involves re-creating a facsimile of the tattoo as its own asset and applying it to an animated recreation of the player.

You got two issues here.

Not art?

Something that is an “original works of authorship fixed in any tangible medium of expression” is protected by copyright in USA. There is no question of artistic value so there is no slippery slope.

It’s not a slippery slope. Can you copyright a haircut? Because if you can, and the hairdresser copyrights the haircut in the game, then yea, the hairdresser would have a case. But you can’t copyright a fade or cornrows or something similar that a million people wear.