You might like to hear of some direct evidence from an African perspective. I was giving a lecture on the orgins of the blues in the USA, and I was playing some of the earliest recordings I have, including Robert Johnson.
One of the students that year was Noel, from Dakar in Senegal- a djembe player and brilliant all round musician.
He arrived a few minutes late, and having missed the intro, did not know exactly what I was playing.
I could see that he was looking confused, so I asked him what the problem was.
"Why are you playing music from Mali?" he asked, "that was ......."
I wish I could remember exactly what he said but it was something like "Al Valous music from Mali".

I should say that, at that time, Noel spoke Wolof, Arabic, French and as a poor fourth, English - he was not always easy to understand.

Two things strike me- one that even by the early years of the 20th century, blues still was recognisably African, to a native African musician.
Secondly- did I just hear the original name of The Blues?
Cheers
Dave