Edward S. Corwin was the McCormick Professor of Jurisprudence at Princeton University in the first part of the 20th century. Corwin is author of several books including The President, Office and Powers in several editions. In the 1957 edition, he wrote (pp 32-33):
But who are “natural-born citizens”? By the so-called jus soli, which comes from the common law, the term is confined to persons born on the soil of a country; and this rule is recognized by the opening clause of the Fourteenth Amendment, which declares to be citizens of the United States “all person born or naturalized within the United States and subject to the jurisdiction thereof.”
Corwin then goes on to discuss how later legislation extended citizenship to persons born outside the United States to US Citizen parent(s).