While shonen anime has a ton of female fans, it's aimed primarily at a young male audience. But that doesn't mean that the creators behind these series are all male. Shonen anime by female creators are more common than you might think, and some of them are pretty incredible.
The most well-known example of a female shonen creator is probably Hiromu Arakawa, whose works include Fullmetal Alchemist and Silver Spoon. There's also Rumiko Takahashi, who wrote and illustrated Inuyasha and Ranma 1/2, and Kore Yamazaki, the creative force behind The Ancient Magus Bride. These aren't just some of the best female-created shonen anime, they're some of the best anime created by women, period.