1) He was quite an entertainer, and influenced "pop" music and dancing (his dancing moves were incredible, and very influential) quite a bit.
2) He came to symbolize "black" people who desperately wanted to become "white" - he was always trying to get his skin lighter, and because he was a celebrity this had an influence on many young "black" people who saw his desire to become "white" and were influenced by this.
3) He also popularized the "Peter Pan syndrome": the boy who just refuses to grow up. He never really did become a mature adult, choosing instead to use his riches to live in a fantasy land populated by boys..... i doubt that he ever actually had sex with any of them, but he famously opined that sleeping with young boys was a "charming" thing to do - like a sleepover!!