Could this have been because he spent his life in the Philadelphia area? Whereas Philadelphia might strike some readers as a backwater of sorts, for the first half of the 20th century and a while beyond, it was a very important place so far as illustration was concerned. That was because the Curtis Publishing Company was based there, close by Independence Hall. And Curtis' stable of magazines included Saturday Evening Post and Ladies' Home Journal, each having huge circulation numbers in their day. So being close to this source of work was no handicap for an illustrator.
Coleman's career is outlined here. The source mentions that one of his art instructors was the "difficult" master illustrator Walter Everett, who I last wrote about here. The link also indicates that Coleman drifted away from commercial illustration in the 1940s to producing religious illustrations, murals, and such in the later part of his career. I will deal with his non-religious art here.
One of the earliest works that I could find.
Somehow this seems to have been done a few years later than the date shown where I grabbed this image, but of course I could be wrong.
The date under Coleman's signature block is smudged, but the woman's gown and hairdo push this beyond the 1920s. The vignette format seen here and immediately above and below was popular with art directors in those days. Illustrators probably liked it too, because they didn't have to spend a lot of effort on backgrounds and settings.
Here Coleman is using outlines and drawing rather than creating a traditional painting.
Interesting combination of framed and vignetted art. I'm pretty sure that the white space was used for a headline and / or text in the magazine.
This magazine dealt with sewing crafts, and so had a somewhat different core audience than the Post, Cosmo and such. Coleman seems to have altered his style to deal with this, quite possibly in line with the art director's wishes.
Yet another two-color vignette.
Just because he was transitioning to religious art didn't mean that Coleman was a total prude.