“First Cow,” set in primitive mud and darkness on the Oregon Trail in cowboy times, is a carefully crafted, realistic anti-western. The film follows two struggling men who become friends, one an almost hapless baker, the other a Chinese dreamer of big ideas and fortunes. Together they stumble upon a means of amassing a modest local windfall, but, of course, fate brews a tougher fate for them. Lead actors John Magaro and Orion Lee sink into their characters’ shoes, the studied, hyper-realistic cinematography is a treat, and the movie is rife with pleasurable viewing snippets. All that said, First Cow clearly paints its storyline on a limited canvas, and the ending is deliberately inconclusive in a way that frustrates, so the overall viewing experience is worthwhile but muted.