The lack of contrast makes it hard to read. I suggest making the pink outline colour a little bit darker, and then making the outline thicker in areas that should get the most shadow (such as where the gut meets the shaded part of the foot,  and where the hands rest on the hips. You could also make the shadow colour darker, but this could prove challenging since it's hard to create contrast without overdoing it when you're using such large areas of a colour.

You have jaggies going on in a lot of places, especially the feet and arms. The...creature...robot... whatever it is is very round and thus should have no discernible texture in its shapes, so jaggies look especially out of place.

The smaller versions look like you just resized the largest one and didn't do any clean-up at all. They're full of broken outlines and other problems. If you want to post smaller versions, then at least polish them to the same level as the original one.

I know multiple sizes are not needed, but that's how I like it. (:

You don't need to post multiple sizes. Just one, un-zoomed, is enough.

You need to crank the contrast way up for this to be readable,