The setting is an Indigo plantation in New Orleans.
Louis says: "But in 1795 these slaves did not have the character which you have seen in film and novels of the South. They were not soft spoken, brown skinned people in drab rags who spoke an English dialect. They were Africans. And, they were Islanders; that is, some of them had come from Santo Domingo. They were very black and totally foreign; they spoke in their African tongues and they spoke the French patois; and when they sang, they sang African songs."
Is this an accurate depiction? I had always assumed that there was an effort to strip slaves of anything related to their heritage, including appearance and language and that dressing, speaking or singing in their native tongue was something that would have been unallowed.
Not in anyway shape or form trying to minimize the reality of slavery, just curious about what it actually may have looked like.
I probably won't answer this question very well but I'll tell you what I do know. It would depend greatly on the location, time period, and especially the plantation owner (the liberalism of the American economy allowed for a lot of individual variance in how plantations were operated and how enslaved people were treated). I don't have specific enough knowledge to speak about Louisiana in particular, but it is not unheard of in primary sources that enslaved African people would speak their own dialects or a creole. Slave labourers singing was certainly common on plantations; the lyrics of the songs of the enslaved is one super interesting oral history source for learning about the time period.
A plantation owner often had significant leeway in terms of how they chose to run their plantation, so some people would have experienced more aggressive assimilation tactics than others. There were certainly many people who were stripped of their home language and customs. Conversion to Christianity was generally a priority for most supremacists. Even so, African people maintained a lot of their culture through the trauma of slavery, including culinary traditions, attire, and music, etc.
In terms of whether this passage is accurate historically, I wouldn't say for certain but I lean on the side of true. At least certainly plausible.
Lit Sidenote: The "soft spoken, dark skinned" people of films and novels that Louis mentions are an archetypal historical misrepresentation commonly seen in Western media up until very recently, which does work in the context of an interview taking place in the [90s?], but also somewhat dates Louis, a very old man who most certainly does NOT keep up with pop culture and probably has not seen a movie for a decade at least.