You made a mistake. You should have said "Unless you accept the CORRECT definition that was well known to the founders..."
The first Congress, made up of many of our founders, wrote in the Naturalization Act of 1790 that citizens born overseas of citizen parents were natural born citizens.
While that comports with the “two citizen parents” requirement of the post 2008 popular definition - it certainly doesn't comport with the “born in country” requirement.
Prior to the election this was not a well known or popular definition of “natural born citizen” - most eligibility debates focused on the dual citizenship angle - or the authenticity of the Hawaii abstract COLB.
Now, of course, we have people claiming that they learned this in grade school - but were somehow conveniently forgetful of that fact until sometime after the election in 2008.