Tarantino by way of Bill, breaks down Superman (although he's somewhat right about the identity being flipped, as his "true persona" is as Superman, and his "disguise" is traditionally as a mild-mannered reporter (although you could also argue Bruce Wayne is the disguise, and Batman is the real persona freed by a mask). Imho he's wrong in his interpretation that Superman must see humans (and by extension his own secret ID (Clark Kent persona), as a coward).
Kal-El's desire to "blend in" as "mild mannered", is to be recognized and accepted as completley separate from his powers, cause that is where he respects and sees greatness in humans who survive and are brave and resilient, despite not having Super powers.