Yes, humanities students can be competitive. MBB firms hire across disciplines because the job requires problem solving, communication, judgment, and learning quickly rather than one specific major.
The business vs non-business majors in consulting recruiting guide explains how non-business backgrounds can position themselves.
Your job is to show analytical ability and impact through coursework, internships, leadership, research, or other experiences. You may need to build business familiarity separately, but you do not need to change majors just to look more conventional.