It doesn’t matter how good your art is. If your parents refuse to understand you, you could craft a masterpiece, and they’d call it an abomination. You could summon the gods of lighting, music, set design and costume for a fantastical fusion of tent revival, lounge act and macabre purgative ritual, and all Mom and Dad would see is a hellmouth.

Generation gaps are well-trod theatrical ground, but in the musical “A Strange Loop,” the candor and daring of writer Michael R. Jackson make the chasm look like uncharted territory. 

In its West Coast premiere, which opened Wednesday, April 24, at American Conservatory Theater’s Toni Rembe Theater, struggling musical theater writer Usher (Malachi McCaskill) and his God-fearing, Tyler Perry-loving parents (played in rotation by an ensemble of six, all “Thoughts” in his mind who pop in and out as different roles) keep rehashing the same argument about his “gay lifestyle” and artistry. Then Thought 5 (Jordan Barbour) as Usher’s father, speaking of himself in the third person, delivers this devastating line: “​​He loves you, but he doesn’t give a rat’s ass about your complexity.”

• Broadway’s unlikely usher: How ‘A Strange Loop’ became a decorated musical

Usher’s isolation is multivalent. Shut out of the musical theater whitestream, rejected on fatphobic hookup apps where the only prospects are “Inwood Daddies” with master-slave fetishes and bored by chitchat with inept tourists at his day job as an usher at showings of “The Lion King,” he writes alone at his keyboard. Imagination is his real world — until it, too, abandons him with an evil cackle, ridiculing his pretensions to self-worth.

The world that Jackson creates to give voice and heft to these inner thoughts and layers, all directed by Stephen Brackett, is a whirligig of invention. A mother, embodied by all those thoughts, speaks as a six-headed Hydra, her stream of consciousness a 24/7 radio station. In the opening number, set at Usher’s day job, the lyrics “Big, Black and queer-ass American Broadway show” and “How many minutes till the end of intermission?” keep duking it out, each with its own musical style, like a fanfare continually interrupting the tick-tock of a cuckoo clock. And those Thoughts, well-schooled in the Ministry of Silly Walks, can make a whole character from a gait: a limp-strut, a seizure-step, a run-in-place prance. 

The trouble with this production is that McCaskill, for all his youthful appeal — he’s currently a college junior — doesn’t yet have the chops to carry a work of this depth. High notes and crescendos alike he treats as hurdles to be ratcheted over. Too often the vocal effect is of a valve from which too much pressure is trying to escape. His phrasing is also two-dimensional, with one lyric exchangeable for any other. A song drives him, instead of him driving the song. 

The lack is especially apparent whenever a Thought gets a moment in the sun. Barbour enlists every pore into his physical characterization. Tarra Conner Jones as Thought 1 coils a song into her fearsome grip. J. Cameron Barnett as Thought 2 builds in countless extra little comic microbeats — a minstrel’s grin, a joker’s about-face — with a percussionist’s precision.

And then there’s that gobsmacking number “Precious Little Dream / AIDS Is God’s Punishment” where Usher pulls out every stop to once and for all win his parents’ acceptance, only to fail spectacularly. 

“A Strange Loop” is itself both that high-stakes bid and the realistically ambivalent carrying-on that must come after. Usher is alone again, more so than before, but he did the thing. Then he told the story and sang the song, shining in Jen Schriever’s lighting design almost as if he’s CGI, yet unvarnished. Here, for one moment, he is free.

Reach Lily Janiak: ljaniak@sfchronicle.com