
Herbert didn’t fail to come up with a better name, he intentionally gave him an ordinary Earth name because Dune is a far-future human civilization, not a novel universe. The Atreides, Harkonnens, Corrinos, they all preserve fragments of Old Earth culture, ie. Jessica, Paul, Vladimir, Duncan Idaho etc... “Paul” is a deliberate choice, and he’s literally only called Paul consistently for the first half of the first book, after that he’s Usul, Muad’Dib, etc.