I guess it depends where exactly the line is for you on that 'subgenre' as the problem you are going to encounter is that basically any good biography almost by necessity is going to be one that at least partly is focused on deconstruction and evaluation of the mythos surrounding him. To that end, maybe Wallace Hettle's Inventing Stonewall Jackson: A Civil War Hero in History and Memory would be sufficient for your purposes? Obviously, historical memory is a big part of the work, but the structure of it is heavily structured around looking at the various biographies done of Jackson in the past, so a lot of it is done specifically in a way that is seeking to peel those away and, yes, 'present a picture of the man'. As such, worth looking into, I think.

Biographies of Stonewall Jackson began appearing shortly after his death. These early biographies were written by members of his staff and drew heavily on personal anecdotes as well as interviews from friends and relatives who knew him in life. The first scholarly biography to appear was Stonewall Jackson and the American Civil War by G.F.R. Henderson in 1898. There have been many biographies written about Jackson in the 20th and 21st centuries but the definitive work is Stonewall Jackson: The Man, The Soldier, The Legend by James I. Robertson, Jr., written in 1997. Robertson's focus is on Jackson the man, not Jackson the general. As such, Robertson does not explain in full detail the battles and campaigns that Jackson fought in. Robertson takes the fog of war approach and when battles and campaigns are discussed, the author focuses on what Jackson saw, heard, and knew at the time. While this work is definitive it is also a challenging read (762 pages of text, not including notes, bibliography, and index). If you are looking for something more accessible I would suggest Mighty Stonewall by Frank Vandiver (1988) or They Called Him Stonewall by Burke Davis (1954), although these works contain some vestiges of the Lost Cause mythology.

I have not read any biography on Stonewall Jackson besides S.C. Gwynne’s Rebel Yell, so I can’t attest to the Lost Cause bent of any of the other books, but I actually found Rebel Yell to be pretty informative.

Gwynne talks about Jackson owning slaves, and although I do wish he went move into depth in the slave owning aspect, I found it a decently objective biography of his entire life with almost no Lost Cause narratives that you might see in books by people like Shelby Foote that toe the line.

Gwynne does built up Jackson’s character more than I’d like, since I personally do not believe Confederates who died Confederates should be held up as American heroes and you seem to have those same views. But I also don’t think he adds to the myths of Jackson by trying to elevate him to something beyond being a good Civil War general and good husband/father.

Personally speaking, I often find it difficult to read biographies on Confederate generals because I view them as traitors to America. But authors of biographies tend to have a deep interest in their subjects, and sometimes that makes them view them in a more positive light than you may. Remember that as you read any biography. When you read any Civil War book, be on the lookout for authors omitting things about slavery, or calling them great Americans, then supplement the missing pieces and questions you have with academic papers and research.

Anyway, I recommend Rebel Yell as a good starting point. S.C. Gwynn is certainly not a Lost Causer