That is not what the term conventionally means.
Anyone born with more than one nationality is not naturally American.
Another country's laws cannot possibly have any bearing on who is eligible for the Presidency. If Outer Slobovia tomorrow passed a law making everyone born on American soil a (dual) citizen of both Outer Slobovia and the US, regardless of parentage -- which they are perfectly free to do! -- then, by your logic, nobody born henceforth would be eligible to be President.
Harris' dual citizenship with Jamaica, extended by the laws of Jamaica, is therefore entirely irrelevant. She should renounce it before taking office, of course. Better yet, let's beat her in November and make it a moot issue.
Justice Waite disagreed
” At common-law, with the nomenclature of which the framers of the Constitution were familiar, it was never doubted that all children born in a country of PARENTS (plural) who were its CITIZENS (plural) became themselves, upon their birth, citizens also. These were natives, or natural-born citizens, as distinguished from aliens or foreigners.”