My experience is that the Game Assets section gets far less traffic than the Games section.
Making some stuff for practice before starting your big heartbreaker project is good advice, assuming you don't already have experience working with the tools you plan to use. But unless the stuff you're making is really good and becomes really famous on the site, I doubt it is going to translate into success for your game.
(Also, I'd just like to point out that all you have made so far is some AI-generated graphics assets.)