Why do animals seem to like stuffed animals (the teddy bear kind, not the taxidermy kind), while people find models similar to people off-putting?

We also like stuffed humans, as long as they're not too human. Dolls, for instance. It's humans that are lifelike, but not quite there, that get you into the uncanny valley. There are a number of theories for why this exists, such as beginning to apply social norms once the object corresponds to our idea of human. Once your 'doll' looks human enough, you stop seeing a doll being a good doll, and see a human being a crappy human, Or because it moves in uncanny fashions or is otherwise 'human-like but wrong,' in a way that triggers some sort of deep revulsion. We start judging them not by the standards of objects, but as humans, unconsciously, and as humans, they don't measure up. A cat likely does not see a 'toy cat' as another cat. On the other hand, a taxidermied cat may set off enough bells to alarm the cat if it is not used to the object. Similarly, we don't see a regular doll as a person.