"I'm the same kind of guy before all this happened"

Michael Phelps is referring to his success in the Olympics. He is stating that despite his success, he is still the exact same individual he was prior to he became an Olympic champion. He is stressing that his success has actually not changed him as an individual. He is still the same kind, humble, and down-to-earth person he was prior to he attained his success. He is reminding us that success does not specify a person, and that it is important to remain real to oneself. He is likewise reminding us that it is necessary to remain simple and grounded, even when one accomplishes terrific success. His quote is a pointer to stay simple and to not let success modification who we are.