See?? Just a few simple things and it improved so much! It's more fun to play as a bird than as a circle.
Also the achievements and shop are a good way to keep the player engaged.
I'd add a coin counter on the UI and I think I'd still replace the platforms for terrain assets and add a few clouds in the background and you'll see how much it would change from your first iteration.
Good job! and I've got a secret, I made a game just like yours last year (well, the same idea at least)