This is the premise of all former theories on the Beginning of the World. But it's just us who can't perceive where they actually come from. There is some Law of higher level we are not presently aware of. The question about the Beginning is really weird. We need to ask about the question.
People ask it, because they have had their own beginning.
Though, not all beings actually have to be alike human nature. The mistake is clear. Because if something doesn't exist, it never does. Hence, it can't be first, before, later, or in the end. Existence is not this kind of being that could have begun earlier, later, or perhaps, not at all.