Hey there - there are many different styles of leadership and ways to show leadership. You don’t have to be extroverted or loud or anything like that to be a leader. My daughter is introverted to the point I’m surprised the interviewers were able to get anything out of her during their conversations. You don’t need to be anyone but who you are in the interviews and your application. Schools want lots of different kinds of personalities.
You mentioned that you do service (leadership/initiative and thinking about others/sharing your talents with others), editor-in-chief of paper (obvious leadership there - learning to delegate, to keep people on task, to work with differing opinions and needs and keep everyone happy), are treasurer of speech and debate (showcasing leadership by stepping up into a key role for your club), and are the class rep for your grade (definite leadership in speaking for others and making sure voices are heard, etc).
There is so much demonstrated leadership in those four activities. Remember to own your accomplishments and your strengths. Instead of focusing on how you might be “letting others down” (which is likely only you thinking this and not others), focus on the things you do well. How have you grown as a person and leader through these roles? What have you learned about your leadership style (maybe you lead by example or are very good at motivating others in some way)? What are you proud of that you have done/accomplished as a part of these roles?