The term meant something else, once. But who, exactly, is the Bimbo here? The term in the early part of the century referred to a lummox, not a lass.
Somehow, that changed. Wikipedia:
It was not until the 1920s that the term bimbo first began to be associated with females. In 1920, Frank Crumit, Billy Jones, and Aileen Stanley all recorded versions of "My Little Bimbo Down on the Bamboo Isle", with words by Grant Clarke and music by Walter Donaldson, in which the term "bimbo" is used to describe an island girl of questionable virtue.
Walter Donaldson was born in Brooklyn, New York, the son of a piano teacher. While still in school he wrote original music for school productions, and had his first professional songs published in 1915. The following year he had a hit with "The Daughter of Rosie O'Grady". After serving in the United States Army in World War I, Donaldson was hired as a songwriter by Irving Berlin Music Company. He stayed with Berlin until 1928, producing many hit songs, then in 1928 established his own publishing company.
As it happens, yes, I do have a copy.