“I wanted to make something Justin Timberlake-y,” he said, adding that the song wasn’t originally intended for this album, added only at the urging of one of his mentors, Elton John.

Even in relating this point, Mr. Sheeran is nothing but unassuming, and singer-songwriter folk is almost definitionally modest: lone performer onstage, often with just a guitar. (He augments the setup with a loop station that he manipulates with his feet.) But even though he may well be the most prominent folk-minded singer in contemporary pop, he’s an open-eared experimenter at core, and saddled with none of the modesty, false or otherwise, that typically go with the folkie role. He began busking and playing small gigs as a teenager, encouraged by his father, who told him he could leave school behind as long as he was working hard toward something. “The thing I was running from was having a mapped-out life,” he said.

“The competitive thing came early on,” he recalled. “Being on a lineup of five singer-songwriters and being, like, ‘I want to kill all of you.’ ” He likened it to Kendrick Lamar’s fiery taking of names on “Control”: “Love for all of you, but I’m here to blow you away.”

He self-released a string of EPs, but his most significant early notice wasn’t for his straight-ahead folk but for a collaboration album with some of the leading lights in grime music, at the time the dominant sound of black Britain, a project that immediately set Mr. Sheeran apart.