The first thing that jumps out to me is the proportion of your image. It's too disproportional, the legs are too long, the arms are too short, and the mid-section is fat too small. I would try to fix those to build upon your image.
The colors are nice, i think the contrast of the clothing to the skin color works well, and i think the pose is good.
I understand you said your technique was 2D, though i would say some basic shading would really help bring this image out a bit more in terms of impact.
Overall, your piece is pretty good, i could see thing being a game sprite or being part of an animation, the simplicity of the piece helps make it usable in those aspects, so generally your piece is well done.
Thanks for the constructive critique! I see what you mean about the proportions needing adjustment.
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