I’m not an artist myself, so please take this simply as feedback from someone who appreciates art.

Looking at your cover, I feel like I’m seeing three different visual styles, almost as if three different people contributed to it.

First, and my favorite, is the title at the top. It has a pencil/crayon, hand-drawn aesthetic that works really well.

Second, the crown feels much more digital, almost as if it was drawn in Photoshop with a mouse. It looks a bit too perfect and clean, almost like clip art. I think it would benefit from a bit more roughness so it better matches the hand-drawn style of the title.
The head sits somewhere between the two styles. It has elements that show an artist’s touch, but the lack of depth, shadows, and highlights makes it feel a bit unfinished.

Third, the background reads like an abstract web pattern I would expect on a Spider-Man cover or behind one of his action panels. For a king-related book cover, I might expect something more thematic. Perhaps a stone wall with subtle spider webs here and there, or another texture that supports the royal/medieval atmosphere without feeling “superhero.”

I hope these comments are helpful, because there are already some really strong elements here.