One tip for the art that would make a huge difference: Learn to fill areas with the colour bucket properly, you have anti aliasing fragments on so many drawings. (The thin yellow lines on baljeets hair here for example)
One way to get rid of them would be to draw the figures with a linewidth smaller than the one you want, then fill the colours in, then draw over the lines with a bigger linewidth, the one you want in the final image, that way the fragments get painted over and are gone. There are other more elegant and technical ways to prevent them but this one is the easiest to do if you are a beginner at using digital drawing programs