[Bjartr]

I think the picasso analogy is flawed. Works by picasso prior to about 1926 are in the public domain, works afterwards are still under copyright. There's nothing about the sale of an original piece that inherently transfers copyright, it depends on the terms of the transfer.

You can buy original animation cells from Disney movies, but try to resell that image commercially and you're probably gonna have a bad time.

AFAICT, NFTs are orthagonal to copyright. But it gets confusing because at least some sellers of NFTs are purposely trying to mislead, by omission if nothing else.