I'm no lawyer, but it looks like the Copyright office does not think the AI generate images have copyright protection, but the human written text of the graphic novel does. And you can't list the AI as a co-author. This probably means your chatGPT texts might as well be public domain & if you can sell it for $5.00, someone else can sell it for $0.05.
https://copyright.gov/docs/zarya-of-the-dawn.pdf
(found via google)