There's already rulings on this holding that the prompt for all LLM or image generator isn't enough to count the result as the human's expression, thus no copyright (both in USA and other places)

You need both human expression and creative height to get copyright protection

Exactly. If I use online Photoshop or whatever, and I use the red eye removal tool, I have copyright on that picture. Same if I create a picture from scratch. Just because someone like OpenAI hosts a more complex generator doesn't mean a whole new class of rules applies.

Whomever uses a tool, regardless of the complexity, is both responsible and benificiary of the result.