Bill Traylor had already lived a full life before he was born as an artist. Enslaved at birth on an Alabama cotton plantation in 1853 and having spent his entire life as a farmer within a 40-mile radius of Montgomery, it was only in his late 80s that he, homeless and alone, parked himself by a bustling intersection in the state capitol’s segregated black neighborhood and began to draw and paint.

Across discarded scraps of cardboard – candy-box tops, old window advertisements – swept memories from his plantation days and scenes of the rapidly shifting cityscape swirling about him. More than a thousand striking, minimalist artworks flowed from his hands in the three years between 1939 and 1942, a rich trove that remains the only significant body of drawings and paintings by a person enslaved at birth.

The new film Bill Traylor: Chasing Ghosts introduces to a wider audience one of the most important American artists of the 20th century, whose life traversed slavery, Reconstruction, Jim Crow segregation, the Great Migration and each’s accompanying tumultuous social and political upheaval. As the art critic Roberta Smith proclaims in the film, Traylor is “probably the greatest artist you’ve never heard of”.

Film-maker Jeffrey Wolf clearly remembers his first exposure to Traylor’s work, just before the landmark 1982 exhibition Black Folk Art in America, 1930–1980, at Washington DC’s Corcoran Gallery. “They were unpacking the Bill Traylors, and that was my first glimpse of them, sitting on the floor before being hung,” Wolf recalled recently to the Guardian. “They just knocked me out. I was in my early 20s, and they had this effect on me that never went away.”

The film took nearly a decade from inception to completion, and one of the main challenges was research. “The records aren’t very well kept, especially for poor, black, indigent people at the time,” said Wolf, who in 2008 made a documentary about the deaf, self-taught 20th-century artist James Castle. “We really had to dig deep.”

But the film-maker Sam Pollard, who directed this year’s MLK/FBI and executive produced Chasing Ghosts, believes Wolf’s documentary comes at just the right time. “In America, there’s been an awakening about the deaths of black men and women at the hands of the police and the notion that this country’s history of racism is deeply embedded,” he said. “Here comes Jeff with a film about an artist who basically lived through all of these different periods and was living also in a place that becomes the center of a major turn in terms of civil rights with the Montgomery bus boycott. Jeff has created a film speaking to the past that is present.”

And it illuminates the oft-overlooked Reconstruction period: Traylor’s art is the sole body of work made by a black artist of his era to survive. “He’s a chronicler,” Wolf says. “He’s telling a story of his time. And he was also a social critic of African American life, and the work’s survival keeps that African American world alive as well.”

Having never learned to read or write, Traylor devised his own visual language rooted not only in his personal memories but also in the folkways of African American culture at that time: singing and storytelling, survival and healing. “He put down this entire oral history in the language that was available to him, which was the language of pictures,” the Smithsonian folk art curator Leslie Umberger says in the film.

Much of his work is oblique, perhaps because it had to be: it was extremely risky for African Americans in the Jim Crow south to express plainly any point of view. Part of the first generation of black people to become American citizens, he was raised in “Bloody” Lowndes county, infamous for the violence inflicted by whites against their black neighbors who sought to exercise their rights and legal freedoms after the civil war. But by employing symbolism, allegory and abstraction, he could address subjects from literacy to lynching.

Traylor himself is likewise an enigmatic figure – few photographs of him exist, and many gaps remain in his biography – but the film strives to encompass the man in full. Married three times and fathering some 15 children, Traylor was, in Wolf’s words, at once “lusty, bawdy, resilient and resourceful, with an ability to fit big ideas into small spaces. [The film is] showing a complete life – he wasn’t perfect.”

Chasing Ghosts also situates Traylor’s life and work in the context of the history at that time and place. “Montgomery is a place that has so much good history and bad history,” says Wolf, who spent seven years of the film’s production going back and forth between the south and his home in New York City. “The south is much more complicated than it appears. I was this white Jewish northerner, but I found common ground with so many interesting people. I would meet the most rightwing person, but when it came to helping me find the cotton field that I could shoot in, they would jump over backwards to help.”

In addition to archival photographs and footage and perspectives from contemporary artists, curators, academics and Traylor’s descendants, the film employs snippets of dance, poetry and prose to emphasize the themes in his life and work, and period music underscores the colorful, kinetic artworks’ comparisons to blues and jazz. The acclaimed tap dancer Jason Samuels Smith was tasked with translating Traylor’s art into dance, and drawings and paintings with figures’ arms and legs akimbo are rhythmically montaged with Smith’s choreography to dazzling effect. “I showed him Traylor’s work, and he came up with poses from the drawings,” Wolf said. “Then on a very hot night and a very hot stage, he just danced his ass off.”

“Some of these documentaries that used to be made about artists were, to be blunt, dull, just dull,” Pollard added. “Jeff came in with some visual motifs and a point of view and took it to another level.”

Although the first major exhibition of Traylor’s work wasn’t shown until 30 years after his death in 1949, he is now regarded among America’s greatest self-taught artists (an imperfect qualifier, to be sure). The groundbreaking 2018 Smithsonian exhibition was the first major retrospective ever organized for an artist born into slavery; last year one of Traylor’s works, a gift from Steven Spielberg to Alice Walker, sold for a record at auction. Scholars continue to study his work, and a lynching memorial and museum opened in Montgomery in 2018, mere blocks from Traylor’s old perch.

But ambiguity persists in Traylor’s work: is the white-face cat that appears in his more violent scenes a witness or a ghost? Is the stovepipe hat atop many of the figures a nod to Abraham Lincoln, as Pollard suggests? And perhaps the biggest mystery is why, in his final years of life, this prodigious output burst from him. Wolf admits he’s stumped: “It’s this transcendent moment when he put together these memories and ancestral roots and history and pours out all this work in a short period of time. It’s kind of a phenomenon. That’s something we didn’t crack, but that’s the magic for him, what he held on to, all those periods of time.”

• Bill Traylor: Chasing Ghosts is available in virtual cinemas and selected cinemas in the US on 16 April with a UK date to be announced