When the United States won its independence from Great Britain the new country had to start from scratch with many things; its form of government, its laws, its currency, even what to call its leader.
Before American independence, leaders of European countries were called kings, queens, emperors, dukes, etc.
The title “president” had not been used for the leader of a nation, only for heads of colleges, and ceremonial titles in congresses, committees, and other such gatherings. An official would sit before the group and serve as the presiding officer. John Hancock served in such a capacity when he was named president of the Second Continental Congress.
Article II of the Constitution established the office and the position of president.
However there was still confusion of how the president should be addressed.
The House was unanimously against anything but president alone. They were afraid that anything more would make the executive leader into a kind of monarch.
The Senate, led by (Vice President) John Adams had many ideas of what the leader of the newly formed United States of America should be called;
“Elective majesty, sacred majesty, elective highness, illustrious highness, serene highness,” Bartoloni-Tuazon said. “The Senate actually went on record as recommending, ‘His Highness, President of the United States and Protector of Their Liberties.’
They fought for three weeks in what was the first case of congressional gridlock.
In the end, at Washington’s insistence, the Senate relented and
“President of the United States.” became the title for the leader of the United States.
Haiti followed suit by naming its leader “president” in 1807. Today, dozens of countries use the title for their heads of state.