It was a well understood term until the 1960s when concerted efforts to undermine it began.
Lots of information at this link
http://www.usnaturalborncitizen.com/index.html
Good read, and while perhaps the original intent, I think there’s some SCOTUS rulings that may not help with the definition since it is not explicit in the constitution. Precedent has too much power.
It was a well-understood term in the 1800s, and it means anyone who is born a citizen. There are only two ways to be a citizen - birth and naturalization. If you are a citizen, and were not naturalized, you can legally become President.
Regardless, the only folks who even REMOTELY care about this issue will oppose her and Biden on a thousand other issues as well.