Sorry, you didn't answer my question.
You asked a series of rhetorical questions, in presentation of your straw men, which aren't worth my time. Here's an example:
Are you saying that it is impossible to learn things in adulthood that you missed out on in childhood? I don't think that's what you're saying?
You're right?
Here's my full answer to this particular question: You're absolutely correct, as nothing I've written would indicate to a normal reader that I consider it to be impossible to learn something in adulthood. Such a position would be insane.
A natural question in response might run, "Why do you assume that greatly delaying, perhaps until adulthood, the learning of (what almost all non-unschoolers would consider to be) foundational knowledge and skills will have no negative consequences for anyone, or, if you like, for anyone but a 'negligible' number of children? Keep in mind that an anecdote about one or a few kids doing fine doesn't mean that an approach will work in general. If you like, present non-anecdotal data, from a neutral source, as part of your answer."
But I'm not asking that question.