By any chance are you getting this info from Dr DPY? He claims surnames belong to certain ethnic back rounds and or religions which is false. I can not even figure out where he is getting these claims from.
The name Levi is biblical. The Levites and the Kohans were priests and yes they did descend from Africa where the tribe of Judah originated from. Just because someone has been giving a biblical name does not mean they were practicing the Jewish religion. The practicing Jews have many different ethic back rounds. From Spanish to Chinese ect. I have people in my family with biblical names that were not Jewish.
As for surname research, you could have African, Indian and European all with the same surname. Just for example the Collins surname. They all come up different because their surname is so common. Just like I have Martin in my family. Martin can be anything. Slaves got the surnames or took on the surnames of their masters.
If you have records of your ancestors being enslaved then they were enslaved. Where you go from here if your ancestors were enslaved is to start researching the slave owner. Slaves were sold like land so you should find deed records. Slaves also got mentioned in Wills.