You asked for comment by those that know what they're doing, so I probably don't qualify, but here's what I see.
Colors:
Something in your tools or process flow is spawning extra colors. Hair, skin, eye, red clothing, other clothing at 3-5 colors each suggests around 16-20 colors overall, but I count 53.
Your color ramps are all constant hue. A common suggestion is to shift the hues as well as lightness to help make the character pop.
The purple pixels on the scrunchy are too small to notice as a distinct color. Consider making the scrunchy all one color.
Character design:
It's unclear in your post if you are responsible for the character design or not.
The hair in front of the face is distracting. I can't figure out where such a large mass of hair is coming from. Or why there's not a part going sideways across her head.
Your figure has an oversized head, which is good for adding expressions to such a small sprite, but she doesn't have a face. No nose, no mouth, only one eye, and half the face covered up by hair. This seems to defeat one of the main reasons for an oversized head.
Anatomy:
Her head is wider (left/right) than deep (front/back). I think it should be the other way around.
Maybe try bulging the hip out instead of in on the two center images. Or maybe just less of a sharp corner.
Other:
On the first and last sprites, the belly lines up with the jacket edge and it makes the rest of the upper torso look odd.
Shoes?
Hope this helps,
Tourist