There are two waysto become a citizen of the United States.
In the first case, anyone who is a citizen by nature of his birth is a “natural born citizen.”
The other way is to enter an become a citizen, or a naturalized citizen.
Rubio, being born in Miami, Florida, is a natural born citizen.
"Natural born" had a meaning in 1787. Place of birth, plus citizenship of parents, were factors in this determination.It is why the phrase even appears in the eligibility requirements for President.
You quote no source for your definiiton. Kindly do so.