[MetaMonk]

What is the minimum copywritable unit?

It would vary across media, but a copyeme (like morpheme, grapheme, phoneme) is very hard to define.

Will it end up being some weird tensor, or something human recognizable?

[Kye]

I think the recent cases on music show it's too variable to encode this way. Sometimes something as common as a common chord progression is enough for courts to decide it's a copy. Sometimes not. Consistency would mean the Amen break is worthy of copyright, and that would cause a lot of people a lot of trouble.