The poem's repetitions reinforce a rhythm similar to the Jazz rhythm, allowing the reader to experience how this rhythm is engaging and realize the importance of Hughes and "Jazz poetry."
We can arrive at this answer because:
Jazz was a very important musical type for American culture and especially for African American culture.
The most striking feature of Jazz is the involving and influential rhythm that this type of music has, which is highlighted by the use of improvisation.
This rhythm and the feeling of unpredictability that Jaz produces are highlighted in Hughes' works through the repetition of words and a non-obvious and well-established rhyme.
With these elements, Hughes allows the reader to experience the rhythm of Jazz, as it allows the poem to have a similar rhythm and musicality.
