Luffy's nuance as a shonen hero compared to others is that he is somewhat a taker in comparison. You can be unknowingly selfish in nature and do things on your own terms and desires. Luffy has always done things that he has wanted, whether or not the people wanted that to happen. By definition this is selfish. In the end he ends up helping others, but the pushing in of itself is selfish. This is just one example. His support for friends is usually out of his intuition about the situation, in a very one dimensional way of persistence that overpowers. He does things out of people's interest all the time as a dominant force. Just because folks eventually open up and believe in him, does not mean the method in of itself isn't selfish.
Luffy is selfish and good natured at the same time. Its like that of a child's sense of the word.
