Elizabeth Cotten (1893-1987)
was a self-taught left-handed guitarist whose highly rhythmic and deceptively simple style flummoxed other guitarists and made her an instant darling of the folk revival crowd.
Thank goodness the guitarist was recorded on film and video on multiple occasions. Before YouTube, you'd have to find a special collections library or happen upon a folklore film festival to have the opportunity to see some of this material. Other bits are I believe from specialist guitar technique videos.
You might know some of her songs already without realizing they're hers; "Freight Train" is probably the best known of her compositions, and she wrote that in her early teen years.
Her music's been covered many dozens of times, by artists such as His Name Is Alive, Opal, Jerry Garcia and Bob Dylan. She didn't achieve much success from her music until the late 1960s, but thankfully she lived long enough to enjoy it, purchasing a home for herself and family in upstate New York and touring and recording regularly up until her death in 1987 at the age of 94.