Plain and simple: the people=US citizens.
The word was thereafter spelled with a lower case, c, to distinguish between Sovereign Citizens and federal citizens, the latter who became subjects of the federal gummint.
The 14th Amendment was written in order to grant privileges and immunities to former slaves who had no official status with the state or the federal government until those who decided to accept the protection of the federal government became its subjects . . . "subject to the jurisdiction thereof."
This should come as a surprise to many, realizing there are two classes of 'citisens' in America living side by side.
Yes, folks. The 14th Amendment only applies to subjects of the federal government.
So, where do you stand?