Stick to the topic please
Interesting that the mod criticised me rather than the person who tried to go off-topic. Not for the first time either...
Anyway, it's very on-topic to discuss how the surname Murzyn originated and the historical background of the name Murzyn. Its cognates in nearby countries suggest a similar pattern of migration. There are equivalent surnames in various countries in Europe; They all suggest migration from far away, and darker-skinned forebears. The surname Turek isn't rare in Poland either.
Even though there's a limit to what people can say about the surname in question without more historical specifics.
Murzyn. Was it inappropriate in 1970s?
It doubtless was a well-intentioned name. Black cats are the best; what will you call the new one?