That might have a little to do with it, but it can't be the entire explanation. Human beings can send a man to the moon in a tin can. This has got to have something to do with intelligence. Ant colonies cannot do that. This comparison is now reminding me of Starship Troopers...

Where's the threshold? For thousands of years humans just hunted and gathered. They used primitive tools. I would argue that ants had more sophisticated behavior at that time.

I don't think that's a good argument. For 90% of the time that homo sapiens has existed we didn't even have pottery

Humans are also causing a planet scale extinction event. That's the opposite of intelligence by any philosophical definition.