Mel Baggs, a disabled writer and artist who became an influential champion of a powerful idea — “that all people are valuable” — through candid blog posts and videos that brought them to the fore of the neurodiversity and self-advocacy movements, died April 11 in Burlington, Vt., at age 39.

The cause was respiratory failure, said their mother, Anna Baggs.

In blog entries, YouTube videos, poems and watercolors, Mel Baggs documented and explored a personal identity that eluded easy labels. “Usually, when people assume things about me, they’re wrong,” they once wrote. “My life is complicated, and it does not follow the standard stories that people expect either of disabled people in general, or of people with my specific conditions.”

Mx. Baggs identified as genderless and used the pronouns sie and hir, although they had little interest in policing people’s language. Some friends and female members referred to Mx. Baggs with more traditional female or they/them pronouns; in general, Mx. Baggs seemed more interested in what people had to say than in the words they used to say it.

Their main focus was on promoting self-advocacy for people with developmental disabilities. Mx. Baggs was autistic and nonspeaking — they used a communication device for most of their adult life — and also used a feeding tube, a cane or wheelchair, and supplemental oxygen to treat frequent lung infections. Seizures remained a lifelong challenge, and severe muscle weakness and an adrenal condition led Mx. Baggs to drop out of college and kept them in bed for months at a time.

It did not keep them from building an independent life, devoted in large part to upending what Mx. Baggs described as “the idea that there is only one kind of real language, real communication, real person.” Their writing and videos placed Mx. Baggs at the vanguard of the neurodiversity movement, which emphasizes the diversity of human experience and minds and rejects the idea of a single “normal” condition.

“Sie fought unceasingly for the principles that all people count, regardless of type or degree of disability,” said Lydia X.Z. Brown, a disability justice advocate and writer, “and that all people deserve to exercise their own agency and to receive necessary care and support, even and especially if others do not understand why. Mel also emphasized constantly that it was most important for hir, and others, to be regarded and recognized as a whole human being rather than reduced to being only the relevant labels or categories.”

Mx. Baggs spoke at conferences on developmental disabilities, worked with Massachusetts Institute of Technology scientists researching autism and — although they were not Jewish — advised Rabbi Ruti Regan, a visiting scholar at the Harvard Law School Project on Disability, on bar and bat mitzvah rituals for adolescents with language disabilities.

“The Torah taught me that we are all created in God’s image,” Regan said in an interview, “and Mel taught me more than just about anyone else how to mean it.”

Mx. Baggs wrote frequently on their blog Cussin’ and Discussin’ (its tagline: “Mel being human in a world that says I’m not”), publishing poems, photos of their beloved cats Fey and Igor, analysis of their experiences in institutional care settings and reflections on the sexual abuse they said they faced as a child.

But they were perhaps best known for a 2007 video, “In My Language,” which showed them speaking in their “native language” — not through words but through actions, including waving their hands, rocking back and forth, rubbing a laptop and running their fingers through water. Mx. Baggs went on to offer a voice-over “translation,” explaining through a computer that they were in a “constant conversation” with their environment.

“The way I naturally think and respond to things,” they said, “looks and feels so different from standard concepts or even visualization that some people do not consider it thought at all, but it is a way of thinking in its own right. . . . Only when the many shapes of personhood are recognized will justice and human rights be possible.”

Mx. Baggs’s nearly nine-minute video drew more than 1 million views online, as well as coverage from media organizations such as CNN and Wired. But much of the public response focused on autism and seemed to treat Mx. Baggs as an object of pity, trapped in their own world. Such viewers missed the point, Mx. Baggs said, writing in a CNN essay that the video “applies to anybody who gets written off because their communication is too unusual,” including “signing deaf people” and schoolchildren who aren’t fluent in English.

“We perceive the world differently,” Mx. Baggs had previously told NPR. “We think differently. And we respond to the world differently. And that goes for all of us, not just some of us.”

Amanda Melissa Baggs was born in Mountain View, Calif., on Aug. 15, 1980. Their mother, the former Anna Lynch, was a respiratory practitioner; their father, Ronald Baggs, was an electronics engineer who designed equipment for high-energy physics experiments.

Mel, who later adopted the name Amelia Evelyn Voicy Baggs, grew up “with a complicated relationship to speech and receptive language,” by their account. They were raised in a rural section of La Honda, Calif., surrounded by redwood trees that became a fixture of their poetry and watercolors.

Mx. Baggs studied at De Anza College in California and Bard College at Simon’s Rock in Massachusetts before continuing their education through books. They soon emerged as a fiery online activist, notably through a website they created in response to an Autism Society of America campaign, Getting the Word Out, which Mx. Baggs viewed as perpetuating stereotypes about autistic people through its black-and-white photos and dour captions.

With the release of “In My Language,” some critics questioned whether Mx. Baggs had exaggerated or faked their disabilities — accusations that Mx. Baggs, and those who knew them from conferences and other events, fiercely denied.

“Sie had a tremendous influence on the commitment in the neurodiversity community that exists today, that this is for everybody, that nobody doesn’t matter and nobody doesn’t have rights,” said Cal Montgomery, a disability rights advocate and longtime friend of Mx. Baggs. “Most of us do not live our values,” he added, “but Mel lived hir values as completely as anybody I’ve ever known.”

Mx. Baggs’s blogs included Ballastexistenz, named after a German eugenics term that was used, as Mx. Baggs put it, “to make us seem like useless eaters, lives unworthy of life.” Many physicians and nurses seemed to treat Mx. Baggs that way, family and friends said.

“For several years prior to her death, Mel was engaged in an escalating fight to convince a failing local support system that her life had value,” Anna Baggs wrote in an email. “It became more and more difficult to secure adequate assistance with necessary activities.”

Last year, Mx. Baggs moved in with a friend, autistic rights activist Laura Tisoncik, whom Anna Baggs described as Mx. Baggs’s “second mother.” Mx. Baggs had been increasingly frail after being hospitalized for the flu in March — they had tested negative for the novel coronavirus — and died at Tisoncik’s home in Burlington.

In addition to Mx. Baggs’s mother, survivors include two brothers and a grandmother.

Almost until the end, Mx. Baggs passed the time with crochet, sometimes making gloves and scarves that they put in plastic bags and left on park benches, accompanied by a note: “If you are cold please take these. I made them for you.”

The handicraft was a way to ease their mind, Mx. Baggs explained in a Ballastexistenz post, and was less physically demanding than painting and violin, their other hobbies. “It gives me something to do with my hands,” they said. “And I need things to do with my hands. I need things that are concrete, things outside the world of words, things that are useful, things that are beautiful.”