It’s always terrible to lose a filmmaker, but it’s especially tragic when the creator in question is just starting to hit her stride. When I say that about director Lynn Shelton, it’s not meant to diminish the work she’d done — nine features, ranging from “Humpday” to “Laggies,” and more than 40 TV episodes, including the first half of “Little Fires Everywhere” — but only to suggest the best was yet to come. That much was certain, since her style was clearly evolving as she went.

Over the span of little more than a decade, Shelton had gone from being a Sundance outsider to one of the indie world’s most interesting voices. Strangely enough, what made her voice so vital was the generous way she gave her actors the chance to use theirs, while shaping their contributions — script ideas, character insights and sometimes fully improvised performances — within the framework of a story that was undeniably her own.

In 2009’s “Humpday,” she deconstructed homophobia by observing two straight male best friends wrestle with the dare to shoot an amateur gay porn video. Two years later, in the superficially familiar sex farce “My Sister’s Sister,” she brought in a pair of bona-fide movie stars, Rosemarie DeWitt and Emily Blunt, relying less on improvisation while still managing to bring out a kind of disarming realism in the process. The same goes for “Touchy Feely,” which brought her back to Sundance in 2013 and demonstrated how her instinct for authenticity translated to a more traditionally scripted dramedy.

As titles go, “Touch Feely” was a play on the massage therapy milieu where the film takes place, but it could just as easily have been Shelton’s brand: Her movies didn’t shy away from embarrassing emotions, but steered straight into awkward territory in an effort to expose and understand modern relationships. She wasn’t alone in that pursuit, but her instincts helped determine the shape comedy would take in the 21st century, dovetailing with — and raising the bar for — creators like Judd Apatow and Paul Feig (who had a much bigger megaphone, but a kindred sensibility).

Shelton was most often identified with the so-called “mumblecore” movement, whose moniker no one involved seems to appreciate. Still, the lo-fi revolution these DIY filmmakers inspired remains undeniable, and Shelton’s contributions were among their most popular. Her career was absolutely a product of a very specific moment in film history, when an unprecedented spirit of teamwork combined with access to relatively affordable digital cameras made it possible for a generation of independent filmmakers to break in. Based in Seattle, she made friends with the likes of Joe Swanberg and Mark Duplass, meeting the latter on a film called “True Adolescents,” for which she was working as the unit photographer.

Unlike many of her peers, Shelton hadn’t gone to film school, not in the conventional sense at least. She’d taken a more high-brow track at New York’s School of Visual Arts, but felt herself drawn to the more populist realm of cinema — though she never “sold out,” sticking to personal, down-to-earth stories about characters that felt like they could’ve been close friends of the director. (Shelton was actually brought in a few times by Marvel to talk about working on “Black Widow,” but don’t read too much into that. The studio famously interviews a wide range of helmers for its projects, many of them far-from-obvious choices.)

Shelton directed three features that hardly anyone has seen prior to making “Humpday,” including Spirit Award nominee “My Effortless Brilliance” and a Christopher Guest-style mockumentary called “What the Funny.” What’s clear from those early practice runs was her instinct for naturalism and a willingness to work off-script. When it came to “Humpday,” she drew up a 10-page outline and enlisted Duplass and “The Blair Witch Project” veteran Joshua Leonard to play the two boundary-testing dudes, shooting the feature on two cameras in just 12 days.

The project caught the attention of “Mad Men” producer Matthew Weiner, who invited her to shoot an episode of the show — her first foray into professional television, where she’d really started to make an impact. “Mad Men” was a famously male-centric series, reexamining the 1960s roots of much of the power games and sexual misbehavior that would launch the #MeToo movement a few years later, and Shelton’s episode, “Hands and Knees,” was no cakewalk — memorable for being the one where Joan discovers that she’s pregnant by way of her boss, leading to a tricky scene in which she weighs the decision whether to abort in the doctor’s waiting room.

These days, directors who break out at festivals like Sundance and SXSW regularly find work directing television, but Shelton got a head start, proving just as funny as her peers in her handling of shows such as “New Girl,” “The Mindy Project” and “Master of None.” Even at the low-budget end (where Shelton largely remained), filmmaking is an expensive task, making it virtually impossible for directors to practice their craft between projects. But in Shelton’s case, TV offered her that opportunity, and the technical aspects of her features seemed to improve by leaps and bounds — though none quite recaptured that very particular chemistry of “Humpday.”

Still, she was on her way up. With 2017’s “Outside In,” she collaborated with the other Duplass brother, Jay, on a raw broken-person portrait entitled “Outside In,” doubling down on her commitment to character and nuanced human connections. Relationships mattered to Shelton, on screen and off. That film marked the fifth time she’d worked with actor Alycia Delmore — a sign of mutual loyalty — while in her private life, she struck up a relationship with comedian Marc Maron, directing several of his specials and casting him in last year’s decidedly weird “Sword of Trust.” That’s not a great film, but it shows growth and a scope that none of her earlier movies had yet attempted, underscoring the potential cut short by her untimely death, at age 54.

It’s impossible to know what insights into ourselves we’ll miss out on now that Shelton’s storytelling days are done. “GLOW” and “Little Fires Everywhere” pointed at more mainstream possibilities still, and yet, it was her comedic sensibility that seemed so central to what we might call “the Shelton touch.” She was capable of orchestrating a very specific, perfectly calibrated kind of audience discomfort — that squirmy, not-sure-how-to-feel sensation you get from shows like “The Office” — while making her performers feel safe. They trusted her, and so did we, while she used laughter to access our sensitive spots and reveal our boundaries.

As an artist, Shelton’s goal was to keep us honest, a sentiment that’s as true for her actors as it is for her audience.