Growing up, I remember when Casey Kasem (on American Top 40) said that the first rap song was “Rapture” by Blondie (1980) after she got the idea from underground clubs in New York.  I thought that was true for the longest time but now if you search it on Google, it’ll show that it’s “Rapper’s Delight” by American hip-hop trio The Sugarhill Gang (1979).  

But why is it that nobody’s giving credit for the first rap song to C.W. McCall for Convoy (1975)?  

Maybe because C. W. McCall doesn’t fit the Hip Hop image… and sang Country Music?