Is all vibe-code in the public domain?

This document [1] from the US Copyright Office is making the rounds where I work, along with the claim that full-on vibe-coding isn't eligible to be copyrighted in the US. And if that is the case, is it even possible to assign a license to it? Ergo, is it in the public domain?

Note that in this document the copyright office addresses the case of image generation, where a person were to throw prompt after prompt at the model until they get something they like, and then possibly add some more prompting to make some adjustments to get the final image. And they plainly state that this is not copyrightable in the US. Isn't this damning to vibe-coding?

[1] https://www.copyright.gov/ai/Copyright-and-Artificial-Intelligence-Part-2-Copyrightability-Report.pdf