Zootopia's premise operates off of a world where humans never existed, but animals eventually evolved to create glittering cityscapes, complex social systems, and funny-looking vehicles. But the idea of anthropomorphic animals living in their own society is nothing new, so who's to say all these stories don't take place in the same universe?
It's a world with a rich history (Kung Fu Panda, Robin Hood, Redwall), various cities (Zootopia), and smaller towns (Arthur, Richard Scarry, Chicken Little), and for some reason the fish (Shark Tale) and various island-dwelling birds (Surf's Up, Angry Birds) have elected to eschew clothing altogether, although many birds living in the cities (DuckTales) only meet the social norms half-way.
