Much of the discussion over the decades of the earliest jazz musicians supposedly being very blues-oriented has basically relied on simple fudging, on taking non-blues songs such as "Careless Love" (which was known to New Orleans musicians because it was known all over the South) to be supposed "blues" songs.

Blues music became a national fad in 1916 and 1917. (The total number of "Blues" songs published and/or copyrighted and "Blues" recordings made, combined, in the year 1915 was about 26. The total for 1916 jumped to about 73.) So all jazz musicians who recorded during 1917 onward were doing so at a time when blues music was already a national fad. The Original Dixieland Jazz Band recording in 1917 or Wilbur Sweatman in 1917 or James Reese Europe in 1919 or Johnny Dunn in 1921 or Kid Ory in 1922 or King Oliver in 1923 (etc.) could be expected to record any blues _because blues music was very popular in the professional entertainment world during 1916 on_ and they wanted to be successful. What the professional entertainment world knew of blues during 1916 on was very largely what W.C. Handy's example told them blues was (not what e.g. Lemon Jefferson thought blues was; they'd never heard of him yet).

What we'd call blues music (with or without the word "blues" in it) was apparently very popular among Southern folk musicians as of 1911.

How interested were New Orleans "jazz" musicians (whoever we think those people quite were) in what we'd call blues music as of say 1905-1911?

One way we can look at this is to notice that normal 16-bar blues, a la Lemon Jefferson's "One Dime Blues" and William Moore's "Midnight Blues," were apparently popular among Southern folk musicians as of 1911. For instance, Texas Alexander sang a 16-bar blues that mentioned getting a Merrow Widow hat, and those were a huge brief fad (a la Crocs) in 1908. Emmet Kennedy recalled that he had already encountered his 16-bar version of "Poor Boy Long Ways From Home" before 1908. In about 1915, when the likes of John Bray and Lemon Jefferson were writing or encountering 16-bar blues that mentioned the Great War, pop songwriters were overwhelming writing 12-bar blues songs, not 16-bar blues songs. W.C. Handy disliked the repetitiveness of lyrics like AAAB, and always avoided the normal 16-bar blues form in his blues, and he was hugely influential on other professional blues writers during about 1913 on because of his great success.

So about 1913 on, don't expect to find the pro music world taking much interest in 16-bar blues (the occasional anomaly such as Euday Bowman aside). Meanwhile, we've got the fact that musicians like these knew the normal 16-bar blues approach: Leadbelly, Furry Lewis, Bo Carter, Rev. Gary Davis, Henry Thomas, Charley Jordan, Mance Lipscomb, Peg Leg Howell, Jesse Fuller, Walter Vinson, Simmie Dooley, Barbecue Bob, Jim Baxter, Daddy Stovepipe, Rufe Johnson, Tom Darby, Blind Boy Fuller, Will Shade, John Bray, William Harris, Smith Casey, Blind Blake, Ed Bell, Tom Bell, Roy Harvey, Reese Crenshaw, Tom Johnson, Elizabeth Cotten, Sam Butler, Bill Jackson, David Miller, Freeman Stowers, Wiley Barner. And these kinds of musicians generally behaved as if 12-bar and 16-bar songs were equally authentically "blues," and often switched between 12-bar and 16-bar in the same tune. All this suggests that there was a time (arguably about 1911) when normal 16-bar blues and normal 12-bar blues were _both_ very popular with Southern folk musicians, but pro musicians weren't yet all that interested in blues music, 12-bar or 16-bar -- or overall we would find many more examples of normal 16-bar blues from pro musicians, as recorded ever.

There are many, many New Orleans jazz musicians who were born before 1900 and eventually recorded. They were routinely asked to record blues. During the '40s on, these older musicians were routinely asked to record the oldest jazz-associated repertoire they remembered. Suppose that New Orleans jazz musicians in general were significantly interested in folk blues during 1905-1911. If so, why are there apparently so very, very few examples of them knowing the normal 16-bar blues approach, while meanwhile the likes of Peg Leg Howell, Charley Jordan, Leadbelly, and Jesse Fuller showed up in recording studios in the '20s-'50s (and even e.g. Johnie Lewis, Thomas Shaw, and Rufe Johnson in the '70s) apparently thinking people who liked blues wanted to hear some of the 16-bar blues they remembered?

(Also note that when it is possible to find pro musicians here and there who knew the 16-bar approach, such as Cow Cow Davenport and Wilton Crawley, those pro musicians have no special relationship to New Orleans, just to the South generally.)