Josephine Baker was perhaps the most famous singer of her time, but many Americans today are unfamiliar with her. Pablo Picasso and Ernest Hemingway raved about her and musicians from Diana Ross to Beyonce have cited her as an influence. Baker was also a champion of the American Civil Rights movement and spoke at the March on Washington in 1963. Now, Denver singer and composer Erica Papillion Posey has written a new cabaret show “Reclaiming Josephine,” in which she stars as Baker. It debuts Thursday night at the Vintage Theatre in Aurora.