Hi Lisa -
Pregnancy dreams are some of the most common dreams women have, and yours is no exception. It’s natural and normal for women to dream of pregnancy - from little girls who have never had sex to post-menopausal women who are wondering “How in the heck did this happen?” Similarly, given your relationship status, I suspect your dream is a combination of looking forward to the time when you will be pregnant - so you dream of it - coupled with the accompanying thought of “This can’t be true - I’m not in a relationship!” And then the dream continues with you actually believing that you are pregnant, with your mind racing for a possible explanation.
In light of your dream report, I doubt the black baby has any racial significance - i.e., that you are subconsciously attracted to Black men, for example. But I do think that, because the baby is unplanned and unaccounted for, that this may account for his color being unusual or different than what you would expect.
I think your hormones may be "kicking in," Lisa, encouraging you to start thinking about raising a family. If you peek around in the “Pregnant” category (and “Fear of Pregnancy”) in the Women’s section, you’ll find you have lots of company!