I feel like TAing can definitely be leadership. You’re tutoring other students, especially if you held review sessions for exams.
Club positions are meh. It’s easy to BS but I hosted some events here and there, started a fundraiser for the club and represented it. I still consider it leadership of some sort.
I got my own research project to work on in an Orgo lab. I’d consider that leadership.
Leadership is subjective to an applicant, if you feel like you “led” the group then you can list it and explain why