Mel Baggs, whose forthright writings and films about being a nonverbal person with autism made an impact in the fields of neurodiversity and disability rights, died on April 11 in Burlington, Vt., at age 39.

Anna Baggs, Mx. Baggs’s mother, said the cause was believed to be respiratory failure, though numerous health problems may also have played a part.

Mx. Baggs, a vigorous blogger, used the term “genderless” as a self-description. “I like that it just means lack of gender, and has no spoken or unspoken secondary meaning,” read a 2018 entry on the blog “Cussin’ and Discussin’: Mel being human in a world that says I’m not.” Many friends and admirers posting about Mx. Baggs’s death on social media used gender-neutral pronouns, while others used the traditional feminine ones.

Gender issues, though, were not Mx. Baggs’s major concern. Of more urgency was conveying that people who think and communicate in nontraditional ways are fully human, and that humanness is a spectrum, not something that can be reduced to a normal/abnormal dichotomy.

Many people were introduced to these ideas through Mx. Baggs’s short film “In My Language,” posted on the internet in 2007 and given wide exposure through coverage on CNN. For three minutes it shows Mx. Baggs fiddling with the knob on a dresser drawer, rubbing against a book and more. Then it offers “a translation,” as the film puts it.

“The previous part of this video was in my native language,” a synthesized voice says. “Many people have assumed that when I talk about this being my language, that means that each part of the video must have a particular symbolic message within it designed for the human mind to interpret. But my language is not about designing words or even visual symbols for people to interpret. It is about being in a constant conversation with every aspect of my environment.”

By the time “In My Language” was posted, Mx. Baggs had already drawn considerable attention in the autism world for creating the website “Getting the Truth Out,” a response to an awareness campaign by the Autism Society of America called “Getting the Word Out,” which Mx. Baggs thought made autistic people objects of pity. Part of that attention was skepticism about Mx. Baggs’s claims. Autism online forums can be caustic, with sharp divisions among various factions, and the harshest detractors have accused Mx. Baggs of being a fake.

But certainly the writings and films that appeared under the Baggs name challenged a lot of conventional thinking.

“There are many important parts of autistic culture that trace back to Mel’s writing and influence,” Ari Ne’eman, a disability rights activist and author, said by email, “but one of the most important is hir insistence that the neurodiversity and autistic self-advocacy movements include all autistic people, not just those who could talk.”

“In the early days (and sometimes still now),” he added, “there were lots of people who argued for advocacy only for certain kinds of autistic people, leaving people who couldn’t talk or who had the wrong diagnosis behind. Mel was one of the most powerful voices contradicting that.”

Mx. Baggs, who lived independently in Burlington until about a year ago, died at the home of Laura Tisoncik, an autism activist whom Anna Baggs described as Mel’s “second mother” and who had taken Mx. Baggs in as cascading health issues and problems with home health services made living independently impossible. Ms. Tisoncik (who emphatically rejected the idea that Mx. Baggs was faking anything), summed up Mx. Baggs’s core idea in a phone interview. “There are no unimportant people,” she said.

Amanda Melissa Baggs was born on Aug. 15, 1980, in Mountain View, Calif., to Anna Marie (Lynch) Baggs, a respiratory practitioner, and Ronald Baggs, an electronics engineer. Childhood was spent in La Honda, Calif., about 45 miles south of San Francisco, where the redwood forests made an impression that was reflected in the poetry Mel wrote as an adult, Anna Baggs said.

Mx. Baggs, who later adopted the name Amelia Evelyn Voicy Baggs and became known as Mel, for a time attended De Anza College in California and Bard College at Simon’s Rock in Great Barrington, Mass.

“I grew up sometimes able to speak and sometimes not,” Mx. Baggs wrote on another blog, ballastexistenz, “and with a complicated relationship to speech and receptive language.”

As an adult Mx. Baggs increasingly came to use a communication device, employing both a keyboard and picture symbols, and posted frequently. The topics addressed ranged far and wide.

Mx. Baggs was concerned that autism awareness had become a trendy catchphrase, “whether it’s parent groups who throw the word ‘autism acceptance’ around to sound current but don’t actually accept the slightest thing about their autistic children, or whether it’s autistic people who’ve fallen in love with the words and forgotten the meaning.”

There were blog posts about hir father’s death, hir cats and the “snake words” used in the disabilities-services industry that sounded helpful to clients but, Mx. Baggs said, were actually harmful. (“Apologies to actual snakes,” one of these entries noted.)

Anne Corwin, a friend for 15 years, said one thread was that the world’s idea of normal is precarious.

“A major theme running through many of Mel’s writings (especially the ones describing harrowing experiences with abuse, institutional settings, and medical neglect) was: this could happen to any of us,” she said by email “It could happen to you, to your loved ones, and it will keep happening until we decide as a civilization to do better.”

In addition to Anna Baggs, Mx. Baggs is survived by a grandmother, Elizabeth Lynch, and two brothers, Jeremy and Shane.

Mx. Baggs took the name of the ballastexistenz blog from “ballast existence,” a concept employed in Nazi propaganda to justify killing people with disabilities. “Mel was treated as life unworthy of life,” Ms. Tisoncik said. “Except she was very worthy of life.”