Yes, I agree, in just pointing out how difficult is to understand that. Theoretically, it’s not like a human-level intelligent insect couldn’t exist.
My thinking to challenge myself/ourselves: Then how do whole colonies decide and plan resources? When to gave truce or war with the neighbouring colonies (of same or completely different species?). Their war strategies resemble human wars without technology/weapons. They also cultivate insects, plants, and fungi. Some within colonies plan, deceive, and try to develop a new queen (instead of the queen doing it in purpose/strategy).
Having brains as such imho is part of the problem as it adds a lot of complexity for humans to relate to.
But even our brains don’t work and govern alone, major organs have a complex nervous systems of their own (complex in the sense of not having a centre).
Not as a direct comparison to insect, but eg cephalopod brains are also vastly different, yet clearly highly intelligent.