“Obama’s mother did not have to be 21 for him to be a natural born citizen. She was a citizen, she was in a U.S. State when he was born, thus he is a natural born U.S. citizen regardless of her age.”
Apparently, the law at the time of his birth said otherwise.
No it didn’t.
The law that is quoted is in reference to a person born outside the U.S. to one parent that was a citizen and a parent that is not a citizen.
If you were born in the U.S. to a citizen, this point of the law didn’t come into question.