What are all of these boxes with numbers inside of them and how do I get rid of them?
That’s your ruler data showing dimensions. To delete them, tap N to open your sidebar, then go to annotations and delete the ruler data.
Is there any way to disable the ruler function completely?
Don’t use the Ruler Tool? You have it selected in the Toolbar.
It’s actually called the Measure tool and you might have accidentally activated it by hitting Spacebar followed by M (or shift+space then M depending on what your spacebar is set up to do by in Prefs). Just switch back to the Select Tool or whatever else you need.