That's a dubious statement. They were residents of the United States and suject to the laws of the United States. Neither Jamacia or India had jurisdiction over them while they were living here. Perhaps true in the 18th Century, but not now and probably not true when the 14th Amendment was adopted.
The Royal Navy had the practice of boarding U.S. Navy warships looking for deserters from the Royal Navy. One of the means of identifying such deserters was by accent. They claimed that persons born in Great Britain were subject to the King and therefore subject to the service in the Royal Navy if they were mariners. The United States took the position that these persons were immigrants to the U.S. and no longer subjects of the King. They had the protect of the United States and were subjects of our country. One of the causes of the War of 1812.
So was Kamala Harris subject to the laws of Jamaica and India when she was born in Oakland, especially since her parents never returned to their native countries? This is a losing political, legal, and Consitutional argument. Although, it could be correct. Persons who were born in the United States, but not subject to our jurisdiction would have parents who were diplomats and perhaps foreign military personnel in the United States for training.
What if Harris takes a trip to Jamaica? What naturally superior case would the U.S. have over Jamaica in terms of claiming first dibs on Harris’ hide if Jamaica decided to draft her into their army and gets its mitts on her before she gets a chance to fly back to the U.S.?