Final answer:
While Enlightenment thinkers laid the groundwork for discussions on freedom and equality, it was 19th-century figures like Frederick Douglass who explicitly condemned discrimination and racial slurs.
Step-by-step explanation:
Enlightenment thinkers such as Voltaire and Jean-Jacques Rousseau were significant figures during the Enlightenment period, offering foundational ideas on equality and freedom; however, their perspectives on discrimination and racial equality were not as progressive by today's standards. Frederick Douglass, an African American leader and former enslaved person during the 19th century, long after the Enlightenment era, more explicitly condemned discrimination and racial slurs. Douglass advocated for the inclusion of all people, regardless of race, in the narrative of America's success and challenged discrimination against various groups, including Chinese immigrants.