Training a neural network algorithm is not equivalent to human learning
That's a stretch, since we don't know exactly how human learning works. Yes we have more than just that one mechanism at work obviously, but that's not to say we're not using the same or similar method as part of our learning process.
original training data can be reproduced completely from models
So can a few savants, more if you take into account those with special training, etc. The ability to do so is obviously latent to our brain.
When they reproduce code which they have previously stored, even only in part, that is a derivative work.
I don't know about you, but I for one have not produced anything 'original' my entire coding career by that metric. I feel confident in saying the vast majority of programmers have not either.
Don't mistake me, I'm well aware LLMs are not intelligent. But I disagree with the idea that their method of learning and their actions is inherently different from what the average person does.