Symbolism, Imagery, Allegory
We hear a lot about flying people in this story—obviously—and while that's well and good, we think the people who can't fly deserve a little attention, too. After all, they're the ones who represent the people who were actually enslaved.
See, "The People Could Fly" represents a fantasy of sorts, the dream of magically up and leaving the terrible realities of life as a slave. But that's all it is: a dream. Like the flying people, the non-flyers are forced to endure unimaginable suffering; for them, however, the only hope for escape is to "wait for a chance to run" (29), making it super clear that flying away from slavery is only fantasy. The reality is much grimmer.
Additionally, the land-walkers are the people who carry this story forward. They're the ones "who [...] told about the people who could fly to their children" (32), passing this inspirational tale on to future generations. Those who can fly don't really need the story, after all—they're free. It's the people who are still navigating enslavement and racism who need a bit of hope to hold onto, which is exactly what this story provides.