Actually is was the "Naturalization Act of 1790" (and 1795), not Nationality Act".
Original Intent is demonstrated in more ways than one by those Acts, being largely created by Founders as they were, being of that era. The sword cuts both ways, in other words. It shows that birth abroad was not originally intended to preclude eligibility to the Presidency in and of itself,...
It showed more than that. It specifically used the term NBC.
but it also demonstrates that citizenship at birth is not necessarily natural-born citizenship, Constitutionally speaking.
Don't know how you come to that conclusion.
The conclusion is reached via the fact that the “natural-born” language was removed at all. Clearly there was a distinction being made. Otherwise, the effort was a pointless exercise. Children of citizen fathers meeting the requisite residency who were born abroad were thenceforth to be regarded as citizens, as opposed to the prior natural-born citizens under the 1790 Act.