> However, do we really understand this existential angst at its root?

Children are a great reminder that understanding existence is irrelevant. Children don't contemplate their own existence, they simply experience and relish that existence. You can't be sure that you have any sort of purpose or destiny, but you can be sure of the ground beneath your feet and the sand between your toes. Children get that intuitively, and for a long time they can't approach life any other way.