They index literal scam and malware, for that matter. But the criminals try very hard and more importantly, very often and we only see the successful ones.
That you took "many hours" over "days" says it all. A digitial artist would take how long to create such pictures? 30 x the time you needed?
As for the guidelines, there is something about ai in there https://itch.io/docs/creators/quality-guidelines#avoid-uploading-excessive-amoun...
There are obviously ai made assets on itch, my opinion is only that ai assets have a higher probability to not get indexed. You did not even change the default resolution of stable diffusion, not even for the "concept art".
Oh, and you currently can not share your free art on opengameart. They will freeze it for unclear legal status.
And not wanting to open a can of worms and yet another ai discussion, but there are people that will debate your claim about "genuine creations". It is like a photographer taking pictures, and printing them on a canvas and then submitting the printed canvas to a gallery of painted canvas. It is a picture, all right. But it is not a painting.
I wonder if your reply is actually AI
That is what an AI would say to avoid suspicion.
But as I said, waiting time is just very long these days. So if your projects will get indexed, it might just take longer.