Humans are the only species on Earth who have so far managed to give to twos up to gravity and actually leave our own planet (not counting the animals we sent up first to check that the coast was clear). As far as we know, we're the only species to do that in the entire universe.
There's a little part of the human spirit that always needs to know more. First, it was just hiking over that next set of mountains to see what's on the other side, then, all of a sudden, you're strapping three blokes into a rocket and firing them at the moon, just to seen what would happen.
Not only that, but we've built a station. In space. A station in space where people live. There's even a website that will tell you exactly how many people are in space at any one time.
Our obsession with all things skywards has led to the final frontiers of exploration to be continually pushed further and further back, even past the boundaries of our own solar system. We've become so good at this whole space thing that, a couple of years ago, as part of the Rosetta mission, we even shot a robot at a comet and hit it.
Out of all the things that the human race has achieved so far, willingly launching ourselves into an environment so hostile that it would make our lungs explode and our eyes freeze over, just to see what it's like, has gotta up there with some of the most badass things we've ever done.