Really getting into this site now, but I am a little disappointed to see that there is no where on here to create our own settings. Would love to see that added as a feature of this site. Anyone agree with me?

When you make a campaign you get large text boxes for detailing things about your setting/world. You have a public notes box viewable by players and a private one for your own use.

Since Adventures are not really something you "add" and this site has a partnership with WotC that makes 3rd Party (Homebrew) content restricted it is very unlikely D&D Beyond will ever be able to make a feature like this even if they had the time.

There are sites like DMs Guild specifically designed for sharing things like this.

Alright, thanks, didn't know those thing. i'm still new here.

You might want to check out World Anvil (worldanvil.com) for building/detailing/documenting your homebrew setting.  I’m a new user there, but so far it’s been pretty useful for keeping things organized.

There are also a number of customizations you can do directly on the character sheet, which may assist with a few of your houserules.