Listeners to Mavis Staples’ You Are Not Alone, the latest album from the Chicago gospel legend who achieved crossover success in the early ’70s with The Staple Singers, might at first think they’d slipped an old record into the stereo by mistake. You Are Not Alone opens with “Don’t Knock,” a track written by Staples’ late father, Pops. It’s interpreted by Staples, some fine gospel-harmony backing vocals, and a touring band that includes the fine blues guitarist Rick Holmstrom—whom Staples has taken to calling “Pops Jr.”—as if trying to erase the years between 2010 and 1971. But You Are Not Alone is ultimately timeless rather than retro. Produced with respectful unfussiness by Wilco’s Jeff Tweedy, who penned two fine songs, including the standout title track, the album reveals Staples in full possession of interpretive skills that have only deepened with the years.