It took several environment-changing events to get our unique kind of intelligence; mammals had to thrive in place of saurs; and then, Africa needed to be split by the Rift and to create the dry savannah.

This forced some apes to climb down the trees and depend on a diet of scavenging for meat, which happened to both increase brain size AND require improved intellect to survive, forcing the evolution of our hypertrophied symbolic brain.

Had this not happened however, other intelligent species could have filled the niche. There's no shortage of other intelligent species in our planet, not just other mammals but octopus and some birds. And then you get hive intelligence, which could equally be forced to evolve into a high problem-solving organism.

Maybe they didn't produce an intelligent species just because they had not the luck of living in the unprecended time in the history of Earth with both high atmospheric O2 and very low atmospheric CO2 we enjoyed for a while, before we started to burn fossil fuels by the gigaton. See https://www.qeios.com/read/IKNUZU

Dinosaurs existed for some 200 million years with no detectable signs of technology development[0]. Presumably, the steady state did not produce a scenario in which the intelligence niche would develop without some other less catastrophic global change event.

[0] Unless that episode of Voyager was right on the mark https://memory-alpha.fandom.com/wiki/Distant_Origin_(episode...

Intelligence evolved at least three times on earth - dinosaurs (leading to corvids, but a raptors already intelligent), mammals and cephalopods (e.g. octopus).

I suspect that any evolutionary environment will eventually create enough variety and instability that some generalists emerge, creating a reward for intelligence. The rise in intelligence from early water-bound life to later forms was likely all driven by more complex and diverse environments.