I don't understand why <ul> isn't nested inside of <h2>?

HI Ryan Straker

The best way to think of this formatting is to visualize it as it would be written on a piece of paper.

The <h2> tag should not be thought of as a container, but rather a formatter. This tag will make the font larger and bolder.
Imagine a menu at a restaurant:
The name of the restaurant will probably be in large print at the top of the menu. This would be like the <h1> tag. Now, lets say you wanted a burger. You would skim the menu looking for the section called "Burgers." The section title would be smaller than the name of the restaurant, but larger then then menu items, so this would be like an <h2>.
If it was all formatted as an <h2> element, than it would all look the same and the point of using an <h2> would become moot.

In short, it's a formatting thing, really. You could use heading tags inside a list to format the <li> tags, but this not in the way you are thinking, and is outside the scope of this post.

Overall, just remember that any heading tag should only contain one line of text and is almost always a title for the section following it.

I hope that this helps make more sense of the purpose and use of headings. If you would like to read up some more to further clarify, the MDN section for heading tags has some nice examples.

Keep Coding! :)