But that's unique in the sense of "you have a bag of ten apples and I have a bag of eleven apples, therefore my bag is unique". It's not qualitatively different intelligence than a dog's, you just have more of it.

I would argue that point. The biological components are the same, but emergent behavior is a thing. So both the scale and the number of connections/way they connect have surpassed some limit after which cognitive capabilities increased severalfold to the point that humans "took over the world".

And arguably further increase in intelligence seems to fall into a diminishing returns category, compared to this previous boom. (Someone being "2x smarter" doesn't give them enough benefit of reigning over others, at least history would look otherwise were it the case, in my opinion)

Probably dumb example, but just by increasing speed you get well-behaving laminar flow vs turbulence, yet it's fundamentally the same a level beneath.