It is a bit more complicated than that, and the legal motivation from the Copyright Office is different than what you describe.

One of the most informative cases, in my opinion, is the Copyright Office's back and forth on Zarya of the Dawn. In their view, even thousands of refining prompts cannot be sufficient to convey copyright protection on an AI generated image since it lacks the necessary control and connection to the person. Suryast is another helpful case. I think they're still very incomplete when you start to consider works like those from Jackson Pollock or, my personal favorite hypo, an artist with a prosthetic that uses statistical machine learning to control the end effector and thus the paintbrush. But those are just hypotheticals for now.

I help chair a conference of IP attorneys and others who specialize in software licensing and AI so we've been talking about this for a while now. We actually just had the conference this week so I can probably share some resources or presentations if people really want to get nerdy about it.

If it's vibe coded, the person who wrote the prompt had minimal impact on the output. They can't, because they don't understand how it works. Their contribution is primarily limited to 1. writing a spec, which is often laughably vague, 2. testing the output to see if it works, and 3. if it doesn't work right, telling the AI to fix the problems.

This was also in response to the 'trust me bro' snide comment. I'm not going to go into detail for something that is practically sealioning.

It also doesn't really define 'vibe code' the way that it is generally understood by developers. Lots of devs use LLMs to do the busywork parts of development without actually vibe coding. It's when you don't understand what your code does that it becomes 'vibe code' - i.e. you're relying on the vibes rather than understanding the code itself to determine if it's good enough. Under that definition, where the prompt typically isn't detailed enough to be considered a significant creative work and the person doing the prompting not only does not - but cannot - understand what it is doing, vibe code is NOT copyrightable, full stop.

If it gets included in a larger work that doesn't fit that definition, then sure, the whole is copyrightable, but then it's just chunks of vibe code, not a vibe coded product - and the contribution in the form of a pull request is not. It is public domain.