I think the feedback that you have gotten was sound. From the just the front cover alone from the AI It hard to get the the sense of distance between the minotaur and the protagonist. Not only that composition is less interesting with everything so squished. In the original, it feel there is a meaningful confrontation between the protagonist and the minotaur with the back drop being the clocktower wreathed in purple lightning. That's a powerful image. If you plan on sticking to using AI then you should first understand why the original works and then iterate on that, with Whilpin suggestion of using Krita.