Nice. Looks good. I'm glad to see there's even more good stuff in the full version on itch.

However, the content shared here (demo version) must adhere to one of the OGA-accepted licenses. The license you've selected is CC-BY, which prohibits extra stipulations: 

No additional restrictions -- You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.

The last line of the Copyright/Attribution notice and the text in the include ReadMe.txt file is restricting others from doing something the license permits:

Selling, copying, distributing or sharing these assets is strictly prohibited, even if modified/edited.

People are allowed to try to copy, distribute, share, or even sell the assets under this license. They probably wouldn't be very successfull since they're required to credit you and link back to this page where any of their potential "customers" would see that it's free. But they're still allowed to try.

Would you be willing to remove that stipulation from the copyright/attribution notice and the readme file? Until then I must mark this as having a licensing issue in order to prevent people from using your assets in a way you may not approve of.

EDIT: Fixed, thanks! :)