What is a super()

Its the other way around, you dont create a Sprite and then assign it to an Enemy, but you create an Enemy which is a Sprite.

class Enemy extends Sprite {
  public _health:Int;
   //...and all the rest like attack, other attributes and ofc the Sprite information itself

  function new(h:Int){
    super();
   _health = h;
   //...
}

At least its a easier solution.