What is it about the way children listen? They hear everything. Just as they can smell onions cooking the minute they walk in the door, they are aware of a range of sound lost to most adults. That is why playing to children is so satisfying: you can feel them paying attention.
That is also why teaching them has to address the full range of what they hear, including overtones, right from the start. Having raised awareness of all that activity there is no way for them to find music boring or repetitive.
My teenage students have much greater attention spans than I had at their ages. That is why they do not quit.
That is also why they are not crushed by being reminded of how much more detail inevitably remains to be worked out. Quite simply, it is utterly and endlessly fascinating.