Assuming we're the stupidest possible biological species capable of starting a technological civilization seems almost (though not quite) as wrong as asserting we're the smartest such. In both cases we're generalizing from a sample size of one.

Well, considering it took us thousands to hundreds of thousands of years (depending on whether you buy that certain, more chronologically recent adaptations played a significant role) to start developing the rudiments of technological civilization, after evolving all the biological assets of intelligence that we have now, I think it's pretty fair to infer that we're not that far above the minimum bar.

A species whose intelligence was far in excess of that necessary to be capable of technological civilization could probably have produced individuals capable of kickstarting the process in every generation once they found themselves in an environment capable of supporting it. By that measure, we as a species proved quite resoundingly lacking.