Everything is relative (apart from right and wrong!). You don't need to be Einstein to understand that. A human is as big to an ant, as a building may be to a human. The world is vast and large - it's size is dominated by massive oceans and continents.
But ever since we've developed the ability to look beyond our atmosphere, it's become more and more apparent that the earth is relatively small. Too tiny to even comprehend, when compared to other planets, stars, galaxies and the universe itself. So just to give you an idea of how tiny we really are, here are some visual aids.