You should work on the timing/spacing of the animation to make the movements less rigid. If I were you I also wouldn't bother shading the character for now and just focus on the making the animation fluid.
Some of the drawings are blocky/awkward. You should probably use the paintbrush instead of line tools, you can still make the lines look clean and its a lot easier to use.
Grey background and grey shirt is a bit too dull.
Also you should make transparent buttons over the stuff where annotation buttons would be.
See lots of potential, keep it up!