CANNES - For artists now closing in on their thirtieth year of sustained filmmaking success, Joel and Ethan Coen still find an inordinate amount of inspiration in failure. From Barton Fink to Larry Gopnik to the Dude himself, underachievement – whether by personal or social standards – has been the hallmark of many a great Coen hero, sometimes more proudly (and more deservedly) than others. To this estimable gallery of schmucks, we can now add Llewyn Davis: a sincerely talented musician, a compellingly gauche social maladjust and, as played by the winningly rumpled Oscar Isaac, star of one of the brothers’ most bittersweet films. 

A wise, wintry ode to artistry lost, found and placed in storage, “Inside Llewyn Davis” finds the Coens perhaps more sympathetic than ever before to the curiosities of their chosen protagonist. Gone is the pointed, arch mockery of a “Barton Fink” or, more recently, “A Serious Man,” replaced by a kind of benevolent fatalism – the film follows its hapless protagonist with the reserved anxiety of an invested parent determined to let their children make their own bad decisions.

Perhaps middle-aged melancholy has finally caught up with the dark indie princes, spurred on by the colossal box office for 2010’s “True Grit,” their most sentimental, studio-flavored release to date. Or perhaps the heart-on-sleeve integrity of pre-hippy 1960s folk music simply rubbed off in the research. None of which is to say “Inside Llewyn Davis” is a soft or overly forgiving film: rather, it’s as generously dimensional an individual character study as anything in their canon.

The setting is Greenwich Village, circa 1961, though Jess Gonchor’s exquisite production design locates it squarely in the shabbily dreamlike wasteland of American kitsch that most Coen Brothers films, regardless of period, tend to favor. These ramshackle surroundings, coupled with the brittle atmosphere of late-winter drag tangibly conveyed at every turn, could as easily be outward reflections of our protagonist’s current New York state of mind: homeless, penniless, nursing the still-raw emotional wound of his former musical partner’s suicide, Llewyn opens the film performing a jolly little ditty entitled “Hang Me,” and seems to be extending the invitation rather too keenly. (The song is one of several poignant, playfully applied folk pastiches written for the film by T Bone Burnett and Marcus Mumford; consider that troublesome Oscar category salvaged for another year at least.)

With his music career having stalled at the next-big-thing stage, and his minor label (essentially a mom-and-pop joint run by two distinctly Coen-esque old coots) having failed to secure one cent of royalties from his debut album (the source of the film’s title), Llewyn is living an essentially temporary life, alternating his extended bouts of couch-surfing between the homes of assorted friends and family: his frosty sister (Jeanine Serralles); vindictive fellow folkie Jean (Carey Mulligan), who’s married to wholesome muso Jim (Justin Timberlake) but may or may not be pregnant with Llewyn’s child; and a kindly academic couple whose unfailing hospitality is returned only with the harshest manifestations of Llewyn’s own social autism. (Oh, and a lost cat, whose resemblance to the skittish feline in 1961’s “Breakfast at Tiffany’s” can hardly be a coincidence.)

The scant narrative is livened up with a misguided road trip to Chicago in the company of a zonked beat poet (Garrett Hedlund, wittily outpouting his own Dean Moriarty from last year’s “On the Road”) and junkie jazzman (John Goodman, whooping it up in his first Coens collaboration in 13 years). Otherwise, however, the brothers’ typically flavorful, verbally spiky script follows a necessarily repetitive circuit, as Llewyn keeps visiting the same old haunts and calling on the same, increasingly frayed allies, in half-hearted pursuit of himself.

Though set 52 years in the past, it’s a setup that will strike a cold nerve with anyone who has ever pursued a career as a self-supporting artist – be it singer or actor, poet or filmmaker – and belatedly faced the possibility that one’s life may not ultimately be shaped by one’s talent. “It’s not so bad being normal,” lectures Llewyn’s homemaker sister, though her gifted loser of a brother is no more capable of that than anything else.

Llewyn’s self-absorption and occasional stridency could make him tiresome company in less charismatic hands, but Oscar Isaac is a genuine revelation in the part: previously best known for “Drive” (in which he also starred opposite Carey Mulligan) and “W.E.,” his soulful gaze and shuffling physical gawkiness strike the ideal balance between movie-star magnetism and Coen-picked eccentricity. With Isaac barely off screen, the uniformly excellent ensemble is very much at his service, though in a touching cameo as a Chicago gig promoter telling Llewyn what he least wants to hear, F. Murray Abraham claims at least one key scene as his own. 

Visually and sonically, meanwhile, this is among the Coens’ richest and most ornate films, with Bruno Delbonnel proving a thrilling substitute for the directors’ vacationing regular cinematographer Roger Deakins: Delbonnel’s trademark palette manipulation and misty focus enhance the bitter seasonal atmospherics, as if the screen itself has frosted over and oxidized in places. (Awards potential isn’t the only good reason to release this in December.) Early on, I feared this beauty was at the service of one of the Coens’ wispier films, though its sensual textures prove part of its very substance. If there’s a sense of slightness that never quite leaves “Inside Llewyn Davis,” that’s for the good in a story that, to some extent, is about life’s slightness, and the scattered moments of bliss – a hit, a song, a round of applause – that fleetingly make it whole.