I dont think there are any rules against using AI because the rules say you can use anything that is not yours as long as you have the rights.
Yes, but isn't that one of the big AI debates? Who has the right to what?
Some AI models are trained off of the work of non-consenting artists and sometimes produce recognizable reproductions of some of those artworks.
Personally, for a no-stakes game jam like this, I figure all that should be required is a credit be given to the AI tool used. Just so others can trace it back if they think something is unoriginal.