If no one existed, who would consider it true? It would have meaning to who? If you showed that statement to some old tribe which doesn't know numbers beyond 3 (Pirahã), they would not know what you mean. If you showed that without translating to some Romans, they would probably have to think about meaning of that sequence of characters. Some ideas (like mathematics or existence of a higher being) are pretty natural for humans, doesn't mean that those ideas mean anything to anyone besides humans, without people there is no meaning, just some clumps of atoms.
