>How's that any different from what happens inside a human's brain when learning?
I don't know, nor does anyone else. So let me ask you - how is that the same as what happens inside a human's brain when learning?
We don't know the details. But it's pretty implausible that the process of learning wouldn't involve the brain having some representation of the thing it's learning, or wouldn't involve repeatedly "copying" that representation. Every way we know of processing data works like that. (OK, there are theoretical notions of reversible computation - but it's more complex and less effective than the regular kind, so it seems very unlikely the brain would operate that way)
And a human who has learned to perform a task has certainly "derived a function that takes some input and produces an output".
I think you can easily make a stronger statement:
We do know that art students spend many hours literally tracing other images in order to learn to draw. We do know that repetition is how the brain improves over time.
"Learn to draw better by copying." - https://www.adobe.com/creativecloud/illustration/discover/le...
Based on that, seems pretty clear to me that the other commenters here would agree (regardless what the brain does internally) that at a minimum, art students are violating copyright many, many, times in order to learn.