......i'm wondering if OP is colorblind bc *esp* with motion it looks pretty clear to me. but if you resolve all the similar colors together + the background you picked for samples, i guess the perception will seem blobby. i mean, you could accommodate for colorblindness and lack of contrast, but at some point you have to focus on making sure your art will translate to all monitors... like without a whole team of artists, and with specific art styles, accessibility can only go so far.
i mean you gave them all moving knee joints, that's not easy
and i view a number of pixel artists who produce animations in exactly this size and subject area. switch your background up and see if it makes a difference?