My brother and I who were born in the USA and were in military service in WWII were always considered plain ‘citizens’ or citizens at birth using your term. Our parents were not naturalized immigrants. However, contrary to your statement we were not the same as/identical to a ‘natural born’ citizen. I can agree that a ‘natural born’ citizen is a ‘citizen’ when born but not that a ‘naturalized’ citizen is a ‘natural born’ citizen. I recall an old adage that goes something like ‘facts are facts just don’t confuse me with your opinions’ and it seems we are at this point in our discussion.
By what reasoning? And by reasoning, I mean law or court decision - because the only ones I know of would consider you a natural born citizen.
The only thing preventing you from running for President is that you presumably have too much integrity to be a politician. ;)