Luffy's desire to become a pirate is symbolic of his idea of "Freedom". Tales from Red Haired Shanks fuelled this idea to the point where becoming the "King of the Pirates" would allow his to achieve ultimate freedom.
Although he hasn't achieved the status as king yet, he has had a taste of true freedom. After Bonney questions why Luffy has white hair in his Yonko bounty (5th Gear) his response is "Oh, That's What I Look Like When I'm Free!!".
Other pirates in One-Piece are typically aggressive and would willy-nilly murder and pillage as stereotypical pirates. Luffy's ideology however contradicts that, which does make him out to act non-pirate like but that's to do with how other pirates are contrasted.