I really like the atmosphere here, cute and tranquil, the parallax scrolling clouds were a nice touch, and the animation on the main character was quite adorable.
If I were to nitpick, the art for the main character noticeably stands out from the other art, I think it's the outline. That being said - it's really a nitpick, and I for sure couldn't do any better.
This can definitely be expanded upon in my opinion - if you find the time and motivation and no other projects are more interesting at the moment, of course. :) As the other commenter mentioned, a dash could be fun and engaging, maybe power-ups? Maybe even a progression through waves with different things to pick up, including hazards? Although the latter could be bad for the tranquil and cute atmosphere here, too.
Nice work :)