The filmmaker Ava DuVernay has a reputation for tackling challenging material about America’s troubled past. She depicted the bloody fight to achieve equal voting rights for African Americans in her 2014 film “Selma”; examined the prison-industrial complex in her 2016 Peabody Award-winning documentary “13th”; and portrayed the wrongful conviction of five teen-age boys of color in the miniseries “When They See Us.” But “Origin,” her first narrative feature film in five years, may be her most ambitious work to date. “This breaks every screenwriting rule, every rule of filmmaking that I know,” DuVernay tells David Remnick. “Origin” is an adaptation of the journalist Isabel Wilkerson’s best-seller “Caste,” a complex analysis of racism and social structures. “Caste” lacks a cinematic narrative structure, and so “Origin” positions Wilkerson as its subject as she navigates the intellectual journey of the book. DuVernay felt compelled to make this movie now, in part because she thought that its message would be vital for audiences in a Presidential election year when the understanding of America’s past is very much at issue. “We have to wake up and focus—focus on what is happening,” DuVernay says. “And I want this film to contribute to that conversation.”