Very cute! I agree with what Vrine said, you could make the shadow a bit more higher contrast, especially near his arm to define it more! On top of that you have something we call "jaggies." Around the edges you should try to make them ease into the curve, rather than random sharp turns? The single pixels make it look sharp/jagged, hence the name, they make him look bumpy rather than soft.
You have a really good start here, keep it up and I look forward to what you do in the future!
Very cute, I love Kirby :) My advice would be to use higher contrast in the shading!
Thanks for the tips! now I see clearly where I can improve.