They also could provide insurmountable opportunity. You'd have a huge advantage against enemies if you could develop some kind of mutualism with the beasts of nature.

Imagine living on top of an elephant. I guess you would attend to its skin and health, in exchange for a great defensive position, free transport, the potential to live off dying cells and moisture, etc.

Fast forward a very long time, and you might have humans controlling all the animals of the wild, which would have developed their own ways of survival, territory and rivalries. Animals which lack this 'army' of humans tending to them would die out. Wouldn't be so different to now...