I disagree that the President’s first job is to protect Americans.
His first job is specified in our most honorable document, perhaps the greatest document ever written in all time.
It is to ‘SECURE THE BLESSINGS OF LIBERTY’.
That’s it.
You’re partially right. The preamble specifies 4 purposes for our government, not just for the president: (1) insure domestic Tranquility, (2) provide for the common defense, (3) promote the general Welfare, and (4) secure the Blessings of Liberty to ourselves and our Posterity.”