In fairness, Poirot was absolutely modeled on Holmes, as were many Golden Age detectives. An aspect of Holmes as the competitor, survived even though Doyle meant to present him as the teacher who inspired people to study forensics.

Also, in fairness, Dorothy L. Sayer's Lord Peter Wimsey is way closer to Jennifer's definition of a hero: he overcomes PTSD and gets married.

It was a kind of clunky character arc, but she did attempt it and inspire many Kinsey Milhone type characters later.