This is why overzealous complaints about cultural appropriation are ultimately self-defeating. For a cultural phenomenon to fully blossom and flourish, it must pass through many hands. Attempts to keep cultural output pure and proprietary deny that output the ability to reach its potential. The dominant culture in American society is made of myriad influences—for the very reason that it takes from all.
In helping to invent Rock and Roll, Chuck Berry did not just create a great symbol of America. He created a great art form of the world. And he did it by taking what he needed musically, regardless of the demographics of its creators. He took advantage of the good in both Blues and Country. In so doing, he created a musical lingua franca—a style of music that is not only enjoyed, but also created in almost every culture on Earth.
Viewed in this way, Marty McFly choosing Chuck Berry’s “Johnnie B. Good” as the seminal example of 1950’s rock is a great and deserved compliment. After all, the real joke is that Marty invents Rock and Roll—a new sound so vital and compelling that it stuns the crowd and becomes arguably the most popular form of music in the world. “Back to the Future” is just a movie. Chuck Berry was real. With an open ear and an open mind, he helped to create an art form that is, above all, human.