Questlove, member of The Roots, the house band of “The Tonight Show,” viral sensation via his role in Jimmy Fallon’s “Music on (Kids) Classroom Instruments” cover song gimmick, is quickly emerging as THE music documentarian of the moment.

He compiled and directed “Ladies and Gentlemen…50 Years of SNL Music,” and introduced America to the lost history of “Black Woodstock” with his “Summer of Soul” documentary about Harlem’s 1969 Black music concert series.

With his latest, “Sly Lives!” he spearheads a new appreciation for the act that “stole the show” at the original Woodstock — Sly and the Family Stone — and the Black genius who led and formed it, Sylvester “Sly” Stewart, aka Sly Stone.

Questlove interviews the members of the group — Sly’s sister Rose, Cynthia Robinson, Greg Errico, Larry Graham and Jerry Martini — to tell the story of how another major force in Black music got his start in the Black church, performing gospel music before becoming a stand-out DJ on San Francisco radio, record producer and hit maker and then band leader of the chart-topping cultural phenomenon, Sly and the Family Stone.

The least-known corner of this history might be Sly’s rapid evolution from music prodigy to sideman to producer, where he made hits for San Francisco’s The Beau Brummels and recorded the first versions of the most famous songs by The Jefferson Airplane, as Grace Slick talks about Sly’s work with her first band, The Great Society.

But it was Sly’s formation of an egalitarian, integrated seven piece band with men and women, horns and multiple singers fronted by guitarist/keyboardist and iconic frontman Sly that immortalized him. Sly and the Family Stone were “like nothing else” you heard on the radio in their day.

And musicians from George Clinton to D’Angelo, Chaka Khan, Nile Rodgers, Andre Benjamin and Q-Tip sing their praises and admit the influence on their own music by the man and the band that directly spawned Parliament Funkadelic and later Prince and the Revolution.

D’Angelo marvels at how Sly was the first major Black artist to realize “You’ve always got to be three, four or five steps ahead of everybody else.”

Questlove charts the band’s meteoric rise, bringing message music to “The Ed Sullivan Show,” where Sly boldly introduced their act with “Don’t hate the black, don’t hate the white. If you get bitten, just hate the bite.”

“Dance to the Music” to “Hot Fun in the Summertime” to “Everyday People,” their most popular songs were funky, infectious, danceable sing-alongs that age like fine wine.

But if we know anything about such documentaries, we know that most every musical rise is accompanied by a fall. Questlove subtitles his film “Aka the Burden of Black Genius” as he asks his many interview subjects to endorse his thesis that rising above racism to popularity in white culture at large is a too great weight for many a performer to bear.

Sly fell into drugs and reclusion just as the band’s novelty was starting to wear off, hastening their decline as tastes changed. They might have been an enduring force in the disco era and beyond, but Sly and the broken-up band just disappeared.

You’d read anthologies like “The Rolling Stone Illustrated History of Rock & Roll” and the top writers of their era would wax lyrical about the genius of Sly and push a sort of J.D. Salinger myth that grew around what he was doing and his possible musical comeback.

“Sly Lives!” revives that mythos, celebrates the highs and mourns the loss of a career third act that might have been. But Questlove has the unfailing instincts to end his story with a touch of triumph, which just makes us impatient for his next history lesson. That one will be about Earth, Wind & Fire.

Rating: TV-16, profanity, discussions of drug abuse

Cast: Rose Stone, Cynthia Robinson, Greg Errico, Larry Graham, Jerry Martini, Chaka Khan, Nile Rodgers, Andre Benjamin, D’Angelo, George Clinton, Q-Tip, Jimmy Jam and Terry Lewis, with Clive Davis and Sly Stone.

Credits: Directed by Questlove. A Hulu release.

Running time: 1:51