And we probably suck at these tasks about as much as it's possible to suck and still build a technological civilization, because otherwise we would have built it at an earlier point in our evolution.

I don't think this follows. Humans spent thousands of years in near stagnation (the time before the dawn of agriculture is but one example). It isn't clear what caused technological civilization to take off but when new discoveries occurred almost looks like some sort of nearly random process except that the probability of a new discovery or invention increases as more discoveries occur. I'd almost consider modeling it as a biased coin which starts off with an extreme bias towards tails, but each time it turns up heads, the bias shifts a bit in the heads direction. Something like P(heads on the nth flip)= (1+k)/(10^5 + k) where k is the number of previous flips that came up heads.If that's the case, then the timing doesn't by itself tell us much about where our capacity is for civilization. It doesn't look that improbable that some other extinct species might even have had the capability at about where we are or higher but went extinct before they got those first few lucky coin flips.