It seems like there are plenty of African-Americans named Patrick or Sean, but hardly any with names from other national origins - I've never heard of an African-American named Giuseppe or Gerhardt or Vladimir. Why the prevalence of Irish names in particular?
hardly any with names from other national origins
I disagree with the premise of your question, which ignores the immense historical popularity of French names in the African American community. French given names like Dominique, Angelique, Andre, Francis, Antoine and Leroy have been prevalent for generations.