How did Buddhism challenge Hinduism?

Buddhism challenged the traditions of Hinduism primarily in its denial of a centralized religious authority. The authority of Hinduism lay in members of a priestlike class called Brahmins whose status was determined by family lineage. Buddhism, in contrast, endowed all of its practitioners with the potential to reach enlightenment.
Buddhism more implicitly challenged the narratives of Hinduism in its lack of focus on creation myths, origin stories, and other dogmatic abstractions. It rejected the unfairness of the caste system and oppressive gender norms which Hinduism perpetuated and, in turn, drew its power from. Though they were far from reaching modern conceptions of "justice" in terms of social and economic equality, Buddhists believed that gender and caste formed no basis for achieving enlightenment.