Take away the naturalization act and NO ONE is a citizen either natural born or naturalized. It is a decision fork not a loop. It is the naturalization act that defines the RULES OF NATURALIZATION (per US Constitution Article 1 Section 8).
The naturalization act says people who meet cases A - G are citizens at birth and do not require the naturalization process to be citizens, [end of decision branch].
Those that do not meet cases A - G are not citizens at birth and therefor, must be naturalized [jump to the criteria for becoming naturalized]
There were citizens of this country before the first naturalization act was ever passed, so this statement is clearly in error.
“Take away the naturalization act and NO ONE is a citizen either natural born or naturalized.”
To the contrary, take away the naturalization act and there are those who are citizens: those born in country with parental US citizenship. No law is required for their citizenship, they are natural born.
“At” is a point in time.
“By” is causal.
§ 1401 declares who shall be nationals and citizens of United States AT birth. Such persons are citizen at birth BY law.
The causal agent is operation of law. That law may vary causing a person to either be a citizen at birth or not at all.
A person born in country to citizen parent is a citizen BY birth.
The causal agent is birth. This person is always a citizen, this has never been doubted.