Black music of the 1950s was, in a word, seminal. There were a lot of great artists, but it would be folly to try to list them all. What was great about the black music of the 1950s is that the seminal artists were not all found in one genre.
Ella Fitzgerald had been in the recording game for a while but reached probably the peak of her career in the 1950s. In 1956, she started recording songbooks with Norman Granz. In 1958, her work paid off in the form of two Grammys. A lot of singers have tried to emulate her, but it is safe to say there will never be another Ella Fitzgerald.
If you want seminal black music of the 1950s, you need look no further than McKinley Morganfield aka Muddy Waters. The man became known as the Boss of Chicago (by none other than BB King) for his lowdown blues. He not only played with some of the giants of blues (Pinetop Perkins, Willie Dixon, Otis Spann, Little Walter), but also influenced some of the biggest names in rock and roll. The name Rolling Stones came from a Muddy Waters song. He also influenced Hendrix, Paul Rodgers (Muddy Water Blues), and Mojo Nixon. Granted, maybe Rodgers and Mojo Nixon are not on the Mount Rushmore of rock, but that just goes to show the breadth of Muddy's influence on both the blues and rock and roll.
You cannot have the story of rock and roll without a couple different labels that promoted black music. Of course there was Chess Records with one of the men who was at the forefront of rock and roll, Bo Diddley. But Bo (with his chunky guitar sound) was not the only one who was leading the path to what we know as rock and roll. Chuck Berry became synonymous with the phrase, and revolutionary Little Richard was blatantly copied by The Beatles. While Chess was certainly important in shaping rock and roll, it was not the only label to leave an imprint.
Before Sun Records had a Million Dollar Quartet, it featured artists like Rufus Thomas (whose song "Bear Cat" rose to #3 on the charts in 1953), Little Milton and Junior Parker. Rufus Thomas and his Sun label-mates may not get the recognition of Chuck Berry, and others, but listen to Rufus and try to tell me honestly that he didn't leave his stamp on rock and roll.
I wasn't alive in the 50s, but I have a lot of 50s black music in my collection. Frankly, that says a lot: that a guy born in Ohio in the mid-70s is still listening to the timeless artists that helped to build the rock and roll era and shape music history.