Sir Lucian Grainge, the chairman and C.E.O. of Universal Music Group, the largest music company in the world, is curious, empathetic, and, if not exactly humble, a master of the humblebrag. His superpower is his humanity. A sixty-three-year-old Englishman, who was knighted in 2016 for his contributions to the music industry and has topped Billboard’s Power 100 list of music-industry players several times in the past decade, Grainge is compact and a bit chubby, with alert eyes behind owlish glass...