Why did Interstellar only win 1 Oscar

Interstellar

As our time on earth is drawing to a close, a team of researchers is undertaking what is arguably the most important mission in human history: it travels beyond this galaxy to explore other habitats in space for humans.

From acclaimed filmmaker Christopher Nolan (“The Dark Knight” films, “Inception”) comes “Interstellar” with Oscar® winner Matthew McConaughey (“Dallas Buyers Club”), Oscar winner Anne Hathaway (“Les Misérables”), Oscar -Candidate Jessica Chastain ("Zero Dark Thirty"), Bill Irwin ("Rachel's Wedding"), Oscar winner Ellen Burstyn ("Alice doesn't live here anymore") and Oscar winner Michael Caine ("God's work & the devil's contribution") in the leading roles. Wes Bentley, Casey Affleck, David Gyasi, Mackenzie Foy and Topher Grace also belong to the ensemble.
Christopher Nolan directs the film based on a script by Jonathan Nolan and Christopher Nolan. Emma Thomas, Christopher Nolan and Lynda Obst produce "Interstellar"; Jordan Goldberg, Jake Myers, Kip Thorne and Thomas Tull are involved as executive producers.
Nolan's creative team is led by cinematographer Hoyte Van Hoytema ("Her"), Oscar-nominated production designer Nathan Crowley ("The Dark Knight"), Oscar-nominated editor Lee Smith ("The Dark Knight") and the Oscar-nominated costume designer Mary Zophres ("True Grit - Retribution"). The soundtrack was composed by Oscar winner Hans Zimmer ("The Dark Knight" trilogy, "The Lion King").