(I'm not a lawyer)
You should be careful about speaking in absolute terms when talking about copyright.
There is nothing that prevents multiple people from owning copyright to identical works. This is also why copyright infringement is such a mess to litigate.
I'd also be interested in knowing why you think code generated by LLMs can't be copyrighted. That's quite a statement.
There's also the problem with copyright law and different jurisdictions.
It is the official stance of the US copyright office.
It was upheld by Thaler v. Perlmutter.
Bartz v. Anthropic and Kadrey v. Meta confirmed with similar rulings.