A few years before 1921
In a time before it was acceptable for women or girls to wear trousers, this seems to me like a humane way to dress an active little girl. The rompers themselves aren't much different from boys' rompers.
But at lunch time, or when one of those old-fashioned, elderly relatives appears, give her hands and face a quick scrub and button on her skirt and you have your little lady (more or less.)
You could even make extra skirts so that you always had a clean one on hand.
This unprinted pattern is unused.
Interestingly, this idea of rompers-and-detachable-skirt shows up for women in the 1930s through the 1950s, when it's known as a "play suit."