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The shtetl Jews of Sadagora in Ukraine didn’t know from platinum records.

They never imagined that a little wordless melody, or niggun, they created — inspired by Hassidism’s joyful attitude toward faith and prayer — would travel around the world, eventually selling millions of copies and becoming a standard tune at b’nai mitzvah and wedding receptions.

Or dreaded cliché, for scholars and musicians dismayed that “Hava Negillah” (“Let Us Rejoice”) has defined Jewish music for generations of diaspora Jews.

Dancing the hora in “Hava Nagila (The Movie)”

This difference of opinion regarding the ubiquitous song is one of many small revelations in “Hava Nagila (The Movie),” Roberta Grossman’s affectionate, bemused slice of cultural archaeology. The documentary has its world premiere on Thursday, July 19, opening night of the San Francisco Jewish Film Festival.

A breezy mix of pop culture Dumpster diving, assimilation history and insightful commentary by a wide-ranging chorus of good-natured experts, “Hava Nagila (The Movie)” is a certified crowd-pleaser. For all its entertainment value, though, the film lacks the gravitas or poignancy to make it stick with the viewer after the lights come up.

That may reflect Grossman’s desire to find a lighter topic following her outstanding 2008 documentary “Blessed Is the Match: The Life and Death of Hannah Senesh,” about the idealistic young Zionist poet who died fighting the Nazis.

The lightweight vibe of “Hava Nagila (The Movie)” might also have something to do with Grossman’s emphasis on American Jewish life in the second half of the 20th century. However, it’s the most familiar and least novel time and place for the film’s primary audience, and invites easy laughs and parody as much as serious analysis.

Grossman was intrigued by the tune’s unknown roots as well as its unlikely and unexpected importance in the careers of Caribbean-American Harry Belafonte, Italian-American Connie Francis and (to a lesser degree) country music star Glen Campbell. But it turns out that the detective work tracing “Hava Negillah” to Ukraine — and the words to Palestine — was completed a while ago.

The matter is not resolved, however, with competing claims among contemporary descendants over who wrote the lyrics: turn-of the-20th-century cantor, musician and pioneering Hebrew lyricist A. Z. Idelsohn, or his then–12-year-old student, Moshe Nathanson (who grew up to be an important composer and cantor).

There’s something very Jewish about this spat over credit (and royalties, perhaps), which the film underscores by showing the principal family members around their respective tables. The domestic settings give the interviews more a whiff of family mythology than objective fact.

The eventual popularity of “Hava Negillah” in the United States corresponds with the movement of Jews to the suburbs, the construction of large synagogues that served as community centers, and the elevation of the bar and bat mitzvah into a peer-pressure spectacle.

The past, unhappily associated with the Old Country and the Holocaust, was jettisoned with the establishment of the State of Israel and its new, strong Jews. Israeli songs and dances, free of any melancholic, Eastern European “taint,” were adopted with pride by American Jews. “Hava Negillah” instantly won fans with its singsong melody and pulse-quickening pace, and became not just a favorite Hebrew song but the only one.

“What’s sad about it is that it represents, for multitudes of people, Jewish music,” says Henry Sapoznik, founder of the long-running Yiddish folk arts program KlezKamp. “And that’s all they will ever know, that’s all they ever want to know.”

The tune’s accessibility and rhythm also made “Hava Negillah” attractive to non-Jewish audiences, allowing Belafonte’s and Francis’ versions to become crossover hits. The public understood and accepted that the song was in Hebrew (the perception of Israel, remember, was substantially different in the 1950s and ’60s), but it no longer carries any ethnic or cultural association, as the film illustrates with YouTube clips of Thai and Chinese performances. (Kitsch is the international language.)

One doesn’t even have to look that far afield. When organists play “Hava Negillah” at the ballpark, does anyone associate it with Jewish life?

For that matter, when the song is played at a wedding or bar/bat mitzvah, does anyone know what the words mean? Or is it enough, as the tongue-in-cheek closing-credits sequence of “Hava Nagila (The Movie)” suggest, that it has a good beat and you can dance to it?

“Hava Nagila (The Movie),” 7 p.m. Thursday, July 19 at Castro Theatre in San Francisco, 6:45 p.m. July 29 at CineArts in Palo Alto, 6:25 p.m. Aug. 1 at Roda Theatre in Berkeley and 4:20 p.m. Aug. 4 at Rafael Film Center in San Rafael. (Not rated, 74 minutes)