Great concept! The art is the weakest part of the game and the thing is I don't think you need to be a good artist to make a good looking game, you can use basic shapes and matching colors
Here is a tutorial on this.
Another thing is the tutorial, you really shouldn't have walls of text in your games unless it's some sort of rocket science kinda game, write the bare minimum the player needs to know to play the game, the player can figure out a lot of things on their own. (You can still write the full guide on the itch page just to be sure no one gets stuck)
Hope this helps :D