Here is Gus Haenschen of St. Louis (born 1889) playing blues piano in May 1916:

https://www.youtube.com/watch?v=jW0RDzLpdnM

(The "Country Club Medley" title on youtube is wrong, it's really his "Sunset Medley.")

Haenschen helped support his family in his teenage years after his father left by playing piano in e.g. silent-movie houses, and he went around befriending people such as Scott Joplin (who included some blues in his "Magnetic Rag" in 1914 himself).