It's a decent start. I honestly recommend giving some sort of indication of the controls, if there are any beyond arrow keys to move. Apart from that, be mindful of visual clarity in the game. You don't want to make your background bright and jump out at the player if you're using the exact same style for the enemies, the player and the objects in the game world.
I assume that the art is all made by you, which is great, but my honest opinion would be to practice some smaller artistic projects before selling your game on graphics or style which is unfortunately what you appear to be doing with a fairly same-y platformer style.
I hope to see you improve, this is but a stepping stone on your path to becoming a great developer!