There used to be humans in Toontown.
It's just that they either went extinct or were driven away to somewhere else, like someplace far, far away. Hence why some of the [newer] Cogs are a lot more human-looking, as they were modeled after them. Heck, the Pacesetter - one of the Regional Managers introduced in v1.3 - looks almost completely human!Prethinker and Major Player are brothers.
The screw nose, Prethinker's last name being an implied B, and Major Player's last name beginning with B (BruBot)… they might be related somehow.