Just read this, some two years late.
Ginger girl has two meanings (outside of the urban east) that I know from childhood; a redhead or ginger-headed (hair sort of a reddish-brown, face often freckled). Ginger girls are what we called the girls who built up school spirit in pep rallies, etc. This meaning may no longer be common.
I have never heard the word used with reference to a Black person, but here in western Canada and adjacent Montana, we never hear African-American speech or urban slang.