The "birthright" citizenship clause of the 14th amendment was intended to clarify the citizenship status of the recently freed black slaves. That intent is clear by contemporary written material.

Now, you could absolutely argue that whatever the intent of the amendment was, it still protects the present-day state of Chinese mothers having zero ties to this country popping over for a few months and giving birth to a fully-fledged American citizen, because the law says what it says. That's a much better argument than saying that the Civil War was fought for the right of transient visitors or illegal immigrants to this country to birth citizens, because that's just absurd.

I think that if you went back in time to 1868 and told Senator Jacob M. Howard that a century and a half in the future, the primary consequence of the citizenship clause of the 14th amendment would be that foreigners from all over the world would attempt to immigrate to the US, even on temporary work visas or explicitly contrary to federal immigration law, with the intent of bearing or begetting a child on US soil who would be legally counted as a fellow-citizen who, upon coming of age, would go to the polls and vote with all other citizens; and that further the parents of this child and their political sympathizers would use the very presence of that child as a justification for why it was immoral to restrict the federal government's lawful authority to control immigration to the United States - that he would've spent a bit more time considering the exact wording of the text.