No, that is actually exactly what I was describing. If it was innate, they wouldn't need to trial and error their way (i.e. learn) to proficiency. But indeed they do.
Your analogy was puberty, which in fact happens with development regardless of trial and error (i.e. learning).
The two developmental processes are clearly distinct. The distinction is that one is a process of learning and the other is not.
I'm talking about being able to walk, you're talking about being proficient. I've said repeatedly that fine-tuning to get better is not incompatible with innateness.
Your analogy was puberty, which in fact happens with development regardless of trial and error (i.e. learning).
The two developmental processes are clearly distinct. The distinction is that one is a process of learning and the other is not.