I’ve heard numerous ideas on that thing that definitively defines us as human beings and they’re all equally as valid as they are invalid. I’ve heard language, opposable thumb and various other explanations.
I’m not here to criticize any of them, but I do like one particular reasoning that does a pretty job of providing insight encompassing the wide spectrum of human behavior. It’s been stated that story-telling is an entirely human activity. The ability to weave together an imagined narrative and present it as truth until the narrative ends. The act of story-telling is an act of deception. A well told story will sweep its audience along and allow him/her to forget for the moment the tempest of everyday life. From this we have the ability to tell the story of our own life as we imagine it should be.
This “self-story” is the wellspring of some of our more unique attributes and achievements. Determination. Faith. Hope. Ambition. I can’t think of another species that collectively looks up at the night sky and declare, “I’m going to be out there someday.” It’s pitifully naive, but it’s the act of creating a story for ourselves and then with great perseverance making that story, that “lie” into truth. When (not if) it becomes true, that lie will leave the domain of the mythical and enter the substantial.
Of course with anything, there is a downside.  But that’s a story for another day. Here’s to hoping that your story is a worthy one once it comes to fruition.