"You can’t know nothing"

Well, you can. In dreamless deep sleep you know nothing, only you, as an individual, are not aware of that when it happens because there's literally no thing. No reference point, no awareness, etc. You may, however, become aware of that ex-post. Also nothing is not non-existence -- nothing already *is*.

"knowing stuff doesn’t quite mean you KNOW stuff"

Naturally. To really know a tree you would have to be a tree. Furthermore, the whole universe you know is merely its rendering within your individual mind. Quite crazy if you consider that the whole cosmos fits into your head. Anyway, all we ever know in relational, relative sense is the content of our mind.

"Knowing as the primary activity is like having the light on"

Yes, but it's not like you always keep your attention there. Well, there are folks who strive for exactly that, e.g. all those blissed out monks who go to great lengths to remain in samadhi, but that IMO defeats the whole purpose of self-realization. Then again, to each their own.

"It’s gotta turn on and stay that way"

It does. But again, it's not like it's always front and center. It's more like an ice cream you have always available in your freezer -- whenever you choose, you will find it there as expected and can have a lick. Which reminds me of a nice scene from the movie Zen -- when Dogen became enlightened, his master told him (and I paraphrase), "Now forget that you are enlightened."