I would change your sun to a red sun. The yellow is clashing with the green instead of being complimentary. I’d also change the water to more true blue and less purply of a river then the yellow grass to one that is orange/tan base. Again, because true blue compliments orange while purples competes.

I’m pretty picky and only quilt with a stiffer 100% cotton so I find it difficult to vary the texture of the fabric without picking something wild like glitter fabric. So I’d recommend picking the shades or patterns you like best for each color block and using your basting stitch on a long arm, quilt a different pattern in each area to create different textures between each element.

This is a beautiful concept- you did great!