He's shown to be a white monkey, from the VR  horror game "scary baboon"
The monkeys in this game don't have legs, and are very similar to the player and characters from the other popular monkey VR game "gorilla tag"
Jeff is shown to be docile, just snoring loudly while sleeping on his sofa, a TV in front of it
He has large eyes, shown to be lines that look like `  just on both sides
His mouth is slightly curved, like a very slight version of :3
He's soft, and quite kind