This question has been akses before but not satisfactorily answered.
According to the Virginia Foundation for the Humanities her ancestry was Welsh and Scottish-Irish. However her complexion was also described as Olive and quoting the Encyclopaedia Virginia
Her olive complexion was considered unattractive, and some white Richmonders compared her to a mulatto or an Indian "squaw."
In images of her she also has many features common to Africana ancestry:
is there any evidence that she had Africana heritage?
Curiously, in this version of your first image she doesn't look anything like as "african" http://civilwardailygazette.com/wp-content/uploads/2011/02/davis.jpg or here http://www.wadehamptoncamp.org/davis67-68.jpg
