What a great question! Not only do I believe we are born with intelligence for most of the reasons already stated, I believe we are born with superior intellect that if properly nurtured allows us to do amazing things.
I also believe that the manner in which our modern society teaches & trains stifles much of our creativity and potential, in effect, dumbing us down.
That is what has brought us to the economic crisis we face in a country run by crooks.
Instead of teaching future generations what we think we know, we should teach them how to use their minds and think for themselves.