Hey! These are actually really good!
With me being a graphic designer in college, it is one of my least favorite things to critique someones art because it comes from their perspective and you don't know exactly what they see when designing it.
Coming from nothing but respect for being able to even make this I'll go ahead and leave a small suggestion on what you could do to improve just a tad bit!
So, when I first saw these avatars (I'm guess thats what these are made for) I thought to myself, "Hmm the proportion of the head to the body is a bit off". By that I mean the head is much smaller than the body. If it were me, I would try to make the head a bit higher rather than longer. (I hope this makes sense). Now, with that being said, the artwork is all around great! If you like it the way they are, I would 100% leave them that way! I hate it when my instructors critique my artwork and literally make me change it so it's something they think is visually pleasing rather than what I think is visually pleasing.
But yeah, great job! Keep up the great work!