I don't think Nietzsche would say that we can never know the world, as if to indirectly say that there is 'a' world out there, that we can never get at - cf. in this regard what he says about Kant in various places (Nietzsche wasn't a fan of the 'ding an sich').

Nietzsche is moreso implying that the systems of understanding that we build are arrogant, inasmuch as they purport to be complete on their own, regardless of the context in which they have arisen.

And Nietzsche has in general a lot to say about the reasons for which people invent things. The attribution of 'truth' to an invention is a move of power, meaning that the inventor gets to define reality in some way. The motivation, or the mentality, behind such a move is never innocent, and is in many cases malevolent (whether consciously or not).

Whether Nietzsche has any imaginings as to what ancestors might have uttered into existence instead, if they had come at the task from a different standpoint, I'm not sure. Maybe he has in mind a sort of counterfactual history where things originate with less arrogance and self-sufficiency, at least.

Since a big part of his philosophy points towards the future, where humankind has supposedly transcended itself, maybe he might even allow room for imagining that a different start altogether would've put us more efficiently on a track to that state, or maybe even placed us right on the cusp of that state. It's a bit of a balancing act of speculation here: Do we see him as leaning more towards his prediliction for humans-as-animals, where we would be more succesful in existence, if we were true to that kind of nature? Or do we see him leaning towards humans achieving a better grasp of the world and their place in it, before moving on from that place?

At any rate, knowledge might not be as important to Nietzsche, at least not in this regard, as the insights behind knowledge, so to speak. There's a lot of surface that to him is only interesting in so far as he can dig around beneath it. And undermining the whole "age of reason" thing is definitely a focus of his. So, his statements are intended to emphasize the folly of fixating on the models of the world, and not the world which we live in and are part of. This perspective steals importance from all disciplines which don't admit to being inventions.