Luffy in this story is smart person. In this story, he still eats the devil fruit, and he will learn about Haki earlier. Shanks saw potential in him, so he tells Luffy what he needs to know about the sea. Shanks still gave him the hat and Benn Beckman gave him a book. It contains all of the things that Luffy needed to know about how dangerous the sea is and how to survive in this world. Disclaimer: I do not own One Piece or any of its characters. The photos and videos I will share in the future do not belong to me, so credit to whoever created them.