What if Earth was the only planet that had intelligent life? It would be extremely chilling for the same facts.
If we died out, and if we found a way to explore farther.
First off, if Earth stopped supporting life, and humans died, what would happen to space and time? Nothing would be intelligent enough to be aware of anything (Unless evolution is real). The entire place we call "outer space" would be empty. This means that if we were alone, nobody really knows how important everything is on Earth!
What would happen if we found a way for infinite space travel? Generations of Human beings flying across the empty place, seeing nothing. It would be extremely upsetting and creepy. Nobody wants to know that they're alone in a field of infinity.
So ask yourself this question; What if our world was the only world with intelligent, or even any life at all?