Speaking as a researcher, the line between new ideas and existing knowledge is very blurry and maybe doesn't even exist. The vast majority of research papers get new results by combining existing ideas in novel ways. This process can lead to genuinely new ideas, because the results of a good project teach you unexpected things.

My biggest hesitation with AI research at the moment is that they may not be as good at this last step as humans. They may make novel observations, but will they internalize these results as deeply as a human researcher would? But this is just a theoretical argument; in practice, I see no signs of progress slowing down.

This is my take as well. A human who learns, say, a Towers of Hanoi algorithm, will be able to apply it and use it next time without having to figure it out all over again. An LLM would probably get there eventually, but would have to do it all over again from scratch the next time. This makes it difficult combine lessons in new ways. Any new advancement relying on that foundational skill relies on, essentially, climbing the whole mountain from the ground.

I suppose the other side of it is that if you add what the model has figured out to the training set, it will always know it.