I noticed long ago that many black female singers used to refer to a man they liked as daddy. Eventually I didn't know if they meant it directly, or if they were implying they were willing to have his baby.
Little Girl in some cases might just be implying that the young lady in question still doesn't know much about the world compared to the singer. It can also be a pet name that simply invokes that he sees innocence in her. In other cases though, I've thought it could easily have a direct meaning.
Of course, when we reach a phrase like "hot child in the city"... err, umm... uhhhh...