So just what is it, this tart and sweet, bubbly and flat, intoxicating and sobering concoction being dispensed from the stage of the Music Box Theater? “Shuffle Along,” which opened with a whoop and a sigh on Thursday night, has been suffering from an identity crisis in the weeks leading up to the announcement of the Tony Award nominations.

It shares its name and most of its song list with a landmark musical from 1921, which means this production should qualify as a revival, right? (That’s what its producers, for strategic purposes involving a juggernaut called “Hamilton,” have argued.)

But wait a minute. The latest version of this show, which features immortal songs by Noble Sissle and Eubie Blake, has a subtitle, dangling like an heirloom earring: “Or the Making of the Musical Sensation of 1921 and All That Followed.” So is this “Shuffle Along” old or new?

The answer is emphatically … both, though not in the ways you might expect.

Directed by George C. Wolfe and choreographed by Savion Glover, both of whom collaborated to electric effect on “Bring In da Noise, Bring In da Funk” two decades ago, “Shuffle Along” is in some ways a variation on one of the mossiest stories from the book of Broadway. You know those beat-the-odds showbiz soaps that regularly surface in gritty black-and-white on the Turner Classic Movies channel?