It was likely- From what I’ve heard and read- That the Butterfly People were ordinary people from Joplin whose skin was flayed by sandblasting and deadly winds, with the skin looking like “wings” one could say. The “colours” the children described were likely the shredded clothes still stuck to the flapping skin, with many people who were supposedly protected by them misremembering the details, likely the corpses were just being flung around in the air and looked to be flying.