Alejandro González Iñárritu’s The Revenant sets out to chart the farthest frontiers of humanity, stranding Leonardo DiCaprio’s bearded, badly-wounded protagonist in the wintery American wilderness and closely observing his desperate quest for survival …and revenge. When The Revenant focuses on the minutiae of survival in the wild – from cauterizing one’s wounds with burning grass to sleeping in a disembowelled horse’s carcass for warmth – it’s compellingly, believably brutal. However, when Iñárritu strays from physical exertion to the conflict between American frontiersman and the country’s indigenous inhabitants, he treads a well-worn path that avoids the thorny issues in the surrounding moral wilderness.

DiCaprio’s Hugh Glass, you see, is an outsider amongst his grizzled fur trapper compatriots. His son (Forrest Goodluck) is a “half-breed” from Glass’ marriage to his (now-dead) Pawnee wife, and Glass’s time living with Native Americans has given him a preternatural tracking ability and knowledge of the land. He speaks the Pawnee tongue fluently, and it’s even implied that he murdered a Commonwealth soldier while defending his family. In other words, he is a representative of a distinctly modern sensibility – the one man in this brutal time who respects and understands the dignity of the Native American people. He is, in short, a good guy.

It therefore follows that his rival, Tom Hardy’s John Fitzgerald, is the bad guy. Fitzgerald is a criminal whose first priority is profit; when Glass is badly injured by a grizzly bear, Fitzgerald is only convinced to stay by his side – along with Glass’s son and a youngster called Bridger (Will Poulter) – by the promise of money. These three men’s remit is to wait for the grievously-injured Glass to die, then afford him a proper burial. But Fitzgerald becomes impatient – and scared of the encroaching Sioux who impelled their retreat – and murder and betrayal eventuates. Thus we have a simplistic conflict – a good man out for revenge against a selfish, evil man.

If The Revenant were a film that truly respected its inspirations, this would be a prime opportunity to stage a moral reckoning. If this were a story by Cormac McCarthy – like, say, his Border trilogy or Blood Meridian, novels that are unmistakable influences on Iñárritu’s film – Glass’s circumstances would drive him to similarly shameful, selfish behaviour, with survival taking precedence over honour. Yet this is a film that draws deeply – stylistically and narratively – from films like Apocalypse Now and Saving Private Ryan, while assuming a simplistic, black-hat-white-hat morality that evades the depth of such works. Glass’s trek through the wilderness never forces him to betray his principles and this is, ultimately, a betrayal of the story that should be told here.

The incorporation of a Native American perspective in this film is commendable. (Though the scene where a Pawnee man gravely intones “You all have stolen everything from us,” represents some deeply-clumsy screenwriting, even if its heart’s in the right place.) It enriches the story to understand that the Sioux men who slaughter Glass’s camp are motivated by a search for the chief’s daughter, Powaqa, rather than mindless bloodlust. But the film’s positioning of Glass as the Great White Man – the one who understands the injustice of the system, the person we imagine we would be if we lived in this time – rings profoundly false.

The film’s truths, meanwhile, lie in its physicality. Emmanuel Lubezki’s camera assumes a dizzying proximity to the action, much as it did in Iñárritu’s Birdman. Our closeness to the action represents perhaps the most enduring qualities of the digital aesthetic, driven by a fluidity and clarity traditionally impossible with film (on a number of occasions, the lens is fogged by DiCaprio’s breath). When we linger on Glass’s wounds, watch as bloody sputum sprays from a gash in his neck as he tries to drink water, or watch as DiCaprio drags his prostrate body desperately through thick snow, the realness of the exertion sings through. For all the failings of the screenplay, it’s hard to deny the craft behind this picture; Leo seems destined to finally win his Oscar here, and while I’m not convinced he’s created a believable character (again, this is largely the screenplay’s fault), his commitment to the role is undeniable.

It’s not all gruesome wounds and guttural grunts, though. Lubezki, a frequent Malick collaborator, borrows that director’s knack for capturing natural beauty in his deific shots of the grandeur of the American landscape. (It’s hard not to think of The New World watching this movie.) He’s aided by a genuinely fantastic, primal score from Ryuichi Sakamoto, Alva Noto and Bryce Dessner. You get the sense that with a better screenplay – and perhaps, a director with a greater sense of restraint – there could have been a great, McCarthyian film here. A blend of the brutal and the poetic. Instead, such moments of poetry are too brief, snuffed out by the clumsiness of the script’s schematics, and we’re left with a formally-formidable, morally-anaemic modern Western.