Now he's definitely more rat-like, less squirrelly... and the pose resolves itself better. When I first posted, I was reading his legs as arms and vice-versa, probably because you said the word "ape." I saw him standing and kind of hunched forward, with big beefy forearms. Judging by Dogmeat's edit, he saw the same thing. Now I see that he's sitting down (before he had his hands beside him, now they're on his knees).
I don't know how to make him look like a chimp with a rat head... it will be very difficult with such a small image. Chimps are very close to humans, so it's tough to communicate "rat-chimp" rather than just "anthropomorphic rat." Extremely long limbs and shaggy fur, I guess. Right now he's too smooth and shiny to be a chimp. Rats and most rodents have short, sleek fur, whereas chimps are furrier. Might be hard to get a convincing fur texture with so few pixels, but you'll have to try.
EDIT: Oh, I see you've changed the thread title to "just rat now." That being the case, I think you've succeeded.