21: Monkey D. Luffy: The Heir of Davey Jones

Different DF fanfic

Luffy's devil fruit wasn't the paramecium Gum-Gum Fruit; it was the Legendary Zoan: Human-Human Fruit, Model: Pirate King! This fruit gave him power over the souls of all the dead pirates, and let him learn the secrets of every man that sailed the seas before him… as long as he was stronger than them, of course!

As such, his years training before going to sea are… much more effective, and, when he sails, he is already a fitting candidate for pirate king, a fact that gets truer as the days go by.