bpy.data would in my view be better described as an global variable rather then a pure module with function definitions, and being a variable the page only links to the type of that variable, which then contains the actual description of the object and it’s attributes (rather then a short example…). From there it’s fairly easy to see that bpy.data consist of attributes such as collections of curves, meshes, scenes etc. And each of the attributes provide futher links to relevant class/type definitions.
I guess it doesn’t answer the question but i think it at least gives an idea of how to navigate the API, and to my knowledge there does not exist a short heirarchy list similar to what you describe. There are however links to subclasses of each type in the documentation, but the structure is not really object oriented with objects inheriting from each other. Instead the structure is rather flat. Look at scene objects for example, the class definition does not have any subclasses, instead data objects are created separately and bound to the object during construction.