it is the human being who notices this vastness, if we weren't here to notice that then the whole concept would be meaningless. Vastness, significance & insignificance are part of human awareness, they don't exist by themselves as ideas 'in vacuo'.

Our knowledge of the universe & the solar system could just as easily be seen as being set up to facilitate human existence - our orbital habitablezone, the protective aspects of Earth's atmosphere and magnetic field, the Earth-Moon system allowing tides and hence life (not to mention the uniqueness of this in our solar system: a single large moon linked to the mother planet), the 'asteroid vacuum cleaner' role of Jupiter protecting us from errant KBOs .. and so on

This is not proof that we are unique, or that God exists - the opposing argument is also valid, that we are the results of this lucky (but totally impersonal) process, so of course we would feel unique and significant. It comes down to faith I suppose, but at least it's fair to say that humanity is not insignifcant in the universe - just vanishingly tiny ..