This is not necessarily true. It is entirely possible to be born of two US citizens and also to hold foreign citizenship. My husband is a naturalized US citizen. He remains a citizen of the UK where he was born, because the UK does not recognize the renunciation that is done during the naturalization ceremony.
So, my daughter was born in the US of two US citizens. She is also a citizen of the UK from birth and she holds two passports. Is she eligible to be President? What do you think?
No, not eligible.
One can only naturally be an American when they can’t be anything else.