Katy Perry introduced herself through the promo single called U R So Gay, which was enormously controversial at that time, making the word "gay" more accepted in pop songs later. And just after that she released a WW smash hit single that started her career, I Kissed A Girl, making the moralists fume even harder. Do you know a pop star that took a bigger risk with a debut?
Nope. "Ur So Gay" and "I Kissed a Girl" were intentionally chosen to draw attention to her. If she came out with any other song from One of the Boys she would have flopped.
It's amazing that she had longevity after becoming huge off of such a risky song.
The other big pop girls' debut singles:
Rihanna: Pon de Replay
Britney: ...Baby One More Time
Beyonce: Crazy in Love
Christina Aguilera: Reflection
P!nk (kind of a stretch to include her): There You Go
Madonna: Everybody