This doesn't mean that 'copywrite' extends into my brain. A company can't copywrite what I'm thinking about. And what if I do try to paraphrase something from memory, from a few sources, and happen to spit out a very similar sentence from memory. Am I breaking the law?
To go further. Since all knowledge is pretty much fed into a human from hundreds of books, movies, TV, internet, all pumped into a human from birth. Then everything in the brain is a product of something with a copywrite. So anything produced is some amalgamation of copywrites.
Why not use similar argument for AI. It is clear when asking it to do something like "write a screen play for Othello using dialog like Tarantino, but with bit of style like Baz Luhrmann". That what it produces is 'as unique as a human' would be, or just as filled with things that have copywrites.