The title just kind of says it all, you have options for magic items, spells, races, and even subclasses...... but not classes and weapons outright? I was so excited to make my own class but when I went to DnD beyonds homebrew page, I was confused why there was no option for creating or even browsing Homebrew classes. Can you please add these? I don't know why you just stopped at subclasses.

Because D&D Beyond does not support homebrew classes and mundane gear

Classes and gear are both open-ended, feature defining elements. This means

1. There are no limitations as to what they can do, and thus any tool to add them needs to be able to add anything. This requires programmatic access to the D&D Beyond backend to allow new features to be defined as site wide functionality
2. They define how other things work, rather than are defined by other things. A subclass is defined by the class it's attached to and so has limited scope, making it possible build a template that everything goes into. The same is true for magic items that are built on top of weapons. However, feature defining elements don't have any of those guard rails (see 1)

Basically both of these features operate outside of the templated format that other homebrew uses. This templated approach makes it viable to open up the tools to the community. What isn't viable at this time is opening up the entire backend so people can program in new class features or new weapon properties.