Like others posted, I’ve always regarded common sense as being one aspect of intelligence in general. Common sense is just being intelligent about the routine situations an average person faces.
Hmmmm, if I were intelligent I could calculate how long a train will take to get from point A to point B.
Common sense will tell me to get off the tracks.
I pick common sense.
Like a couple of other posters here i regard myself as fairly intelligent, but decidely lacking in common sense. I’m quite happy with this though, so i’d choose intelligence.
Just a point on this hypothetical 2nd grader. It’s entirely possible (s)he has an IQ that’s “off the scale”. This would make him/her more intelligent than any of us (I’m guessing). Intelligence is a measure of the ability to learn, not what one has learned. So, the only difference between myself and a 2nd grader of equal IQ is time and experience (and, I’m bigger, so I could beat her up and take her cupcakes).
If you’re suggesting that we would never be able to learn beyond the 2nd grade level, that’s different. In that case, I’d take the intelligence (and her cupcakes).