So you think that the people who wrestled with the idea and decided that killing white children and non-slave-owners was not okay were endorsing being victims of absolute savagery? These are the accomplices to villainy in your story?

You think that the black people who didn't kill all the remaining whites until Dessalines personally came to oversee it were swayed by evil? It took his heroic influence to enact the massacre that was the only available option (the only available option despite few taking that option until he not only ordered it but came to oversee it)?

And the Poles and Germans were left alive because whiteness was such pure evil that it blinded them to the fact that the Poles' and Germans' skin color actually was pretty close to that of the French? Among other exceptions--but no, can't spare children, certainly not.

And you can't think of any solution for stopping the search for spared children ("exile"), nor do you think that maybe people might want revenge for killed children?

It reads to me like you want an untainted origin myth, one without the messy mixture of humans breaking free of the horrors inflicted by others, but not without committing a few of their own.