The levels to which humans can learn rationality is in a completely different league from animals, so yes I'll say I'm pretty sure about that. It is like the difference between merge sort and bogo sort, sure they solve the same problem but bogo sorting doesn't work for anything but datasets with a few elements. Animals reasoning chains breaks down extremely quickly, they can do a few steps, but humans can do hundreds or thousands of steps and the reasoning can still be solid and useful even after that many steps.

Nothing of the sort of "rationality" exists in the history of early humans or their ancestors.

I'm not even sure what is this rationality that you're talking about. Because the main narrative of early humans evolves through giant leaps of irrationality.

Even today, most humans are irrational.

> Even today, most humans are irrational.

Compared to what? Compared to animals basically every human has genius level rationality.

The ability to develop and spread farming methods, how to create advanced tools, language, writing etc, is what I mean when I talk about capability for rational thought. Every healthy human has that, no animal is even comparable.

I will admit what I am about to say is more philosophical, and it might not be directly to your point, but hear me out.

There might be an innate rationality in other animals that you are dismissing or overlooking. We all know that when a bird eats a berry it sends the seeds out like a like Johnny Appleseed. Do they use their rational thought to do that? No. But they do not need to.

Or how about the birds who can navigate thousands of miles using the magnetic field of the earth? I do not know many humans who could do that.

Or what about a Killer Whale that can communicate to others 10 miles away without the use of any technology?

Compared to humans, every animal has genius level innate rationality that can compare to no humans.

As humans we are so obsessed with with out own type of greatness but we really need to step back and humble ourselves on the greatness of other (and I will not call them lesser) species.

IMHO, maybe humans have dumbed down and inhibited, and now we need all this technology to survive because we lack the innate ability to do it on our own.

That is a quantitative difference, not a qualitative one. And it is probably related to a synergy of functions.

Quantitative differences becomes qualitative differences when they get large enough. For example, the difference between merge sort and bogo sort are qualitative, you can't sort anything with 50 or more elements using bogo sort while you can sort billions of elements with merge sort.