True, comic-book heroes are childish notions. But this is exactly what lends them a simple, primal purity of meaning. They are a means by which we vicariously confront — and defeat — what threatens us. Batman is our agent, our proxy, our sense that Good exists and that it invariably wins out over Evil. On the streets of Gotham he will be met by Fear (The Scarecrow), Greed (The Penguin), Wrath (Bane) and, inevitably, repeatedly, Insanity (The Joker).
But he — and thus, we — will win. Always. Every time. That knowledge is what he gives us. That is what he is for.