^No, it is fact that slaves used to sing and tell stories in rhyme form to make the time go faster (basically music and poetry). They even used to rhyme about being rich and partying, some rhymed about the current conditions. Just like the club songs and songs about owning money, and the songs conveying a message about certain conditions.
Hip Hop got that part from that. MC-ing used to be just to get the crowd going/moving when DJ's were playing music, but after that MC-ing as an art form developed and took that rhyming about certain topics from the slaves.










