Trust is not simply a matter of truthfulness, or even constancy. It is also a matter of amity and goodwill. We trust those who have our best interests at heart, and mistrust those who seem deaf to our concerns.
That is certainly the point: when the human species was born, on the African savanna, life was pretty good; we could live in harmony with the rest of nature, and that's what I've been calling Eden. The only technologies that humans devised for some 2 million years were fire and the hand ax. That's all. Eden didn't need anything more