Quick Aside: let’s talk about three types of “hierarchies,” as you may be getting confused about that.  The “display list” hierarchy is only how the display manager keeps track of what is “displayed” inside what.

Asking what “objects” are derived from or inherited from another object is a different question, and you’re asking about class inheritance or class hierarchy.

Asking if one “object” is “inside” another object is still another question, and it’s a question about “composition,” which is a specific object-oriented design technique.

All three hierarchies are present in this preloader, and it’s important to keep these three types of hierarchies separate in your mind as you’re trying to understand any ActionScript code.