Why do predatory animals such as bears and cougars typically avoid humans, even though we’re pretty defenseless and “easy” prey?

This is the best explanation that I’ve heard. To most predatory animals, humans just look and smell weird. So they aren’t interested in eating humans.

Hydnellum peckii

This mushroom is edible. But if you saw it, you would likely not consider eating it. It looks too weird. Animals, including humans, eat what’s familiar to them.

That being said, a few animals do prey upon humans. Polar bears are a good example.