She may have had a distant relative who was a moor. So she may have been like 1/64th black.
The UK is a bit different because of all of their colonies. The second or third sons would go work with the East India Company and may marry although obviously that wasn't preferred sending unmarriagable women to India to find British spouses was done for quite a long time.
The widow doesn't become a dowager until their oldest son marries and there's a younger Countess or Duchess to take the title. So the wealthy widow they showed with the toddler son, she was still the countess until her son marries. If she had had a girl and her husband's married brother had inherited then she would become the dowager already.
I also have become an expert due to my regency lit habit and googling while reading when something is interesting, this happens a lot with clothes, I have to picture something so I look at the year and then see what the dresses looked like. They change drastically during the time around the regency period. Going from absurd side hoops with wigs and makeup to basically transparent nightgowns to dresses with sleeves so big that they needed supports to keep them in shape.
This video is facinating