I didn't have any particular age range in mind. Mostly, the idea for the story hit when I was working at something else and got stuck. I remembered the old rule about writing "what you know." Science fiction and bedtime stories came to mind.
This is the kind of story I would have read to my kids when they were pre-schoolers. I wouldn't expect them to know all the words or concepts -- it's more about the sound of the words and the cadence. I'd expect them to ask about things that we could talk about as they (hopefully) fell asleep. My daughter was always more interested in these stories than my son, and thus the Princess was born.
Given that it's short and free, I seriously considered putting up a second version with a Prince -- but that seemed a bit too gimmicky.