Alright, Q. I'll revise my statement like so:
"When The Saints Go Marching In" originated as a 19th century or earlier or a later {early 20th century} Black religious song {"Black" here is inclusive of Afro-Caribbean people as well as African Americans}.

The possiblitity that the inspiration for "When The Saints Go Marching In" could have come in part or in whole from "the white gospel 'When the Saints Are Marching In',[which was first published in] 1896" does not negate the fact that the song was primarily associated with Black religious worship.

I suppose that Q may agree that just because the "White" version was published first, doesn't mean that it was the source for the "Black" version. And maybe this song has both white and black roots.

Be that as it may, I'm interested in reading more about the history and current use of this song.