I've seen interviewees that had resumes and experience that would blow all competition out of the water (theoretically). Yet, they didn't get the job. In a few cases it was because of the negative impression they made with substandard dress and etiquette. You can never be too dressed up but you can definitely be too under dressed.

As far as the leadership thing goes,do you have any mentors? What do you appreciate about them? Mentors are clearly leaders, they have lead you by being a mentor whether they knew it or not. If you really don't know what makes a leader and can't discuss leadership in any way then you probably don;t deserve the job. There are too many people in supervisory positions who are not leaders. I am betting you probably do have some ideas about leadership but just haven't formulated them at this point. Take some time and think it through; look at the examples of leadership you have followed in your life and ways in which others have asked you for advice or mimicked you without having to be asked to do so.