The primary advantage the colonists had during the American Revolution was more belief in their cause. The colonists were fighting for their independence and the ideals of liberty and self-governance, which fueled their motivation and resilience in the face of adversity. This strong belief in their mission often translated into greater resolve and commitment during the conflict.
While some of the other options may have elements of truth, such as participation from African Americans or Native American support (which varied widely), the fundamental driving force for the colonists was their conviction in the righteousness of their fight for independence.