Issue Regarding a TC Question

I hope everyone is doing well. I just stumbled upon a three-blanker TC question that I have a slight disagreement with regard to its solution. In the explanation video for this problem, you said that the first blank should be primeval because of the previously mentioned word ‘Fossil’. But isn’t that like using outside knowledge?

I think, just after the second blanker, this phrase “those of modern humans” is a very strong indicator that, the first blank should be replaced with something that resembles “modern”. In that sense, I think “refined” is a more reasonable answer, given that it has very strong supporting evidence within the passage. And I think it fits the sentence of the passage a bit better too.

What do you think?

It’s not outside information.
The meaning of fossil directly ties with the meaning of primeval.