Before his death in 1989 at the age of 58, choreographer and modern-dance giant Alvin Ailey accomplished many groundbreaking, boundary-busting things. He helped establish modern dance as a popular art form capable of packing theaters and riveting audiences. His troupe, the Alvin Ailey American Dance Theater, was a global sensation. And in his signature dances — 1960’s “Revelations,” 1969’s “Masakela Language,” 1971’s “Cry” for the indelible Judith Jamison — he showcased Black history, Black experiences and Black bodies with passion, ferocity and a beauty that was blinding. It was art, and it w…