Apparently, we have been under a rock for quite some time.
Morris released the design in mid-1882, 18 months after Joel Chandler Harris released Uncle Remus: His Songs and His Sayings in the United States.
It’s amazing how quickly the Brer Rabbit stories skipped across the pond. Not only did Morris have time to come up with this design in less than two years, but also Rudyard Kipling (b. 1865) memorized the stories in school around the same time.