I hear you; but teaching deep expertise is really hard. We can use your example of a child learning their first language. They will really understand it. But people are famously, hilariously terrible at teaching their native tongue. We know how to conjugate, and how to use verbs and adverbs and all the rest. But it’s all intuitive - we have no symbolic understanding of it. If that’s the case, we can’t explain it in words.
Here’s a weird fact: if you look around the room you’re in now, I bet you know what it would feel like on your tongue to lick everything you see. We probably learned that in the “put everything in your mouth” baby phase.
You are an expert. But if you wanted to, how would you teach that? I think the learner would just have to go lick a lot of things for themself.
I believe a lot of real learning is actually like that. When I taught programming, I think I was a frustrating teacher. My students would ask things like “what’s the best way to structure this program?” And I would say “I don’t know. Let’s brainstorm a few ways then you should pick at least one and try writing it like that. Figure it out in code.” I think you become great at programming by licking all the programs you can find. Same with music and art and languages (go have conversations with native speakers).
There is only so much the best teacher can teach. Sometimes you just have to walk around licking things.