"Curtis or Curtiss is a common English given name and surname of Anglo-Norman origin from the Old French curteis (Modern French courtois) which derived from the Spanish Cortés (of which Cortez is a variation) and the Portuguese and Galician Cardoso." Wikipedia
It's true origin is probably lost to antiquity, but I do know that it comes from the word "courteous", if you don't know, that means polite. 😉
"Curtis or Curtiss is a common English given name and surname of Anglo-Norman origin from the Old French curteis (Modern French courtois) which derived from the Spanish Cortés (of which Cortez is a variation) and the Portuguese and Galician Cardoso." Wikipedia