[riverkid]

Riverkid wrote:
I brush my teeth" does NOT mean "I'm doing it right now" to a native speaker of English [ENL]. So the distinction is how we view actions and what 'tenses' we then apply.

Originally Posted by MrPedantic

I wouldn't entirely agree with this statement. There are contexts in which "I brush my teeth" might refer to a repeated action, e.g.
Actually, I'd say that's the norm for the present simple; it describes repeated actions that are habits and routines. Would you not agree, Mr P?
1. "What's the first thing you do when you get up in the morning?" "I brush my teeth."
Correct, this does not mean, "I'm doing it right now".
There are also contexts in which it might refer to a particular action, for instance when recounting an anecdote:
2. I get up. I brush my teeth. I have my breakfast. Then the phone rings. It's my stalker, calling from the phone box outside...
Absolutely, one of the jobs of the present simple, relating a past story to make it seems more alive, but this still doesn't mean, "I'm doing it right now".
But the simple present might also occur in a commentary on a current action:
3. She brushes her teeth...She goes to the kitchen...she boils the kettle...
(Cf. sports commentaries, plays.)
In this usage, a commentary on one's own actions would be equally possible.
Again, I fully agree with you, Mr P. But it still doesn't mean, "I'm doing it right now" in the sense that the normal present continuous does.
When someone asks, "What are you doing?", to inquire about my bouncing a ball,
can I say, "I bounce the ball"; would any ENL reply, "I bounce the ball."

Or do ENLs upon seeing one brush one's teeth, ask,
What do you do?