Who invented the 12 bar blues?

There is no single individual credited with inventing the 12-bar blues. It emerged as a musical form over time through the collective contributions of African-American musicians in the late 19th and early 20th centuries, primarily in the southern United States. Various influences, including African musical traditions, work songs, spirituals, and early country blues contributed to its development. It became a foundation for numerous blues music styles and later influenced other genres such as jazz, rock, and popular music.