Comment by NaiveEmpiricist

I think you just explained the situation, even if you didn't realize it.

LLMs process millions of times more text data and use millions of times more compute power to learn a language, mostly because we know how to do that technologically.

Children use much less text data, but also use a lot of other kinds of data, including interacting with other humans, to learn language. We have no idea how that works. And, on top of that, people can interact with pets of various species in the same way as children, but those pets never learn language.

So, something strange is going on that children can do, but that LLMs and puppies can't. Probably, part of it is that human children are much better at learning by copying what adults are doing, and part of it is that humans evolved to learn and use language. The details of what's going on there is what linguistics is about.