Don't worry about the background just yet. There's a fair few problems I see with this;
- Assuming this creature is supposed to be intelligent, and that it has a brain, and that it's brain is in its head; its forehead, and thus its cranium is too small to accommodate a large, intelligent brain.
- The shading is bordering on pillow-shading, and needs redefinition. Consider the lightsource(s).
- IMO there's too much saturation in the colours. Play with the saturation a bit, maybe tone it down in the highlights or shadows a little.
- The mouth is far too simplified and unrealistic. It looks like a papercut. Look at it and imagine it trying to open, stretch, smile, eat. There's no slack or structure around the mouth to support any of those actions.
- Shoulders need much more work. There's no deltoid-like muscle that gives the arm any base movement. It wouldn't be able to lift its arms! Perctorals aren't connecting with the humerus...it wouldn't be able to hug! Or bitch-slap! There's also very little muscle to allow for neck and head movement.
Basically, whilst it's not an earth life form, let alone a primate, you've given it a hominid-like structure, and so you would do well to study some human anatomy and apply it to the piece to make its body actually physically functional.
