Nietzsche and L'Ouverture
Ah, yes. "Slave morality" and the ex-slave.
I've been reading Genealogy of Morality at around the same time as a few books by some West Indian authors, mainly The Black Jacobins by C.L.R. James & Discourse on Colonialism by Aimé Césaire. The former figures more prominently in this thought but the latter provides the background radiation.
Nietzsche's avatar for ressentiment was the bowing & scraping Abrahamic cleric1 who by necessity had to accede to the powerful, self-affirming aristocracy/warrior class but got his revenge in a centuries-long plot to realign the originally unmoral terms "good"/"bad"2 along moral lines so as to castrate the predatory but free & independent aristocratic spirit.
The target of the screed was a caricature of the modern European man - probably a Brit or German if you're up to snuff on your prejudices - who was overly prudent and totally reactive, unable to simply do as he pleased and furthermore unable to figure out what that would even entail.
That is to say, the starting-point of Nietzsche's study is probably not all that different from that which inspired a different sort of ressentiment, that of the capable, intelligent slave or colonial subject to the preening mediocrities that ran the colonial systems of (say) San Domingo at the end of the 18th century. As C.L.R. James wrote about Toussaint L'Ouverture and those in his orbit:
But for the [San Domingo] revolution, this extraordinary man and his band of gifted associates would have lived their lives as slaves, serving the commonplace creatures who owned them, standing barefoot and in rags to watch inflated little governors and mediocre officials from Europe pass by as many a talented African stands in Africa today.3