Note that Am 14 is only about half the age of the US Constitiution. Note also the text

All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.

The use of PERSON(s) or PEOPLE occurs some 24 times in the body of the US Constitution. CITIZEN(s) appears a mere 11 times and usually paired - as in the description of who can be POTUS.