Two classes of citizens are eligible to be president:
Natural Born Citizens over the age of 35
Citizens at the time of the adoption of the Constitution who are over the age of 35
The point of the second class is that the first class was a null set in 1787. There is no broader implication of the kind you're trying ineptly to draw.
This is not true. Washington, Madison, Jefferson were all considered natural born citizens in 1787. This is clear from Madison's discourse on citizenship on Smith's eligibility.
Anyone born under a Colonial government was a natural born member of that State, even though the State had transitioned from Colony to State.
And historians are in broad agreement that the purpose of the grandfather clause was not to provide eligibility for those born in America. It was to provide eligibility for James Wilson (born in Scotland), Alexander Hamilton (born in the Caribbean) and other foreign-born patriots who had risked their fortunes and lives to bring our country to birth.