Your sprites worl well for animated stuff like the ones above, but if you take the frames separately I can count many problems. Jagged lines, gradient shading on Sonic's head and lack of contrast.
However the worst offender is the Villager, because his face is all jagged. The face is the most important thing to be rendered in a character, in my opinion (because that's the first thing you'll look at on a character, and if it looks weird then there will be problems).
here's an attempt to fix his face, being: making his eyes more evened out, using lighter colors for the eyebrows to maximize space efficiency and toning down on the chin shading for more facial space
However the worst offender is the Villager, because his face is all jagged. The face is the most important thing to be rendered in a character, in my opinion (because that's the first thing you'll look at on a character, and if it looks weird then there will be problems).
here's an attempt to fix his face, being: making his eyes more evened out, using lighter colors for the eyebrows to maximize space efficiency and toning down on the chin shading for more facial space