Milk is literally produced for the benefit of a specie's babies, whereas bananas are produced for the benefit of the banana plant, not for the benefit of monkeys. The only food we consume that was evolved for our benefit is the milk of our mothers. Everything else we eat is predation of other species. There are some instances where that's mutually beneficial, like the example of fruit I gave earlier. But even there the fruit was evolved for the benefit of the plant, not for the benefit of the animal that eats the fruit.