That was my understanding also. But, the issue of being born on a US base overseas or being born to two US parents while traveling, etc. has come up. Then people were saying NBC is anyone who did not have to become naturalized.
I always thought NBC meant born in the USA with two parents that were already US citizens.
You are correct about 2 US citizens and born on US soil. Being born on a base overseas has been discussed; it may depend on whether the person was born actually on base or not. While traveling, not a NBC.
The 2 citizen parents could be naturalized US citizens, but they have to be citizens at the time of the birth of the child, for the child to be a NBC.
People supporting Cruz’s assertion are also supporting 0thugga as NBC (if his purported life was true, which it is not).