Not completely the same thing, but the leader of Congress under the Articles of Confederation was known as the 'President of the United States in Congress Assembled.' Or just the President of Congress. While the name is the same, the president of Congress was a much different office then the current Presidency, functioning more like a prime minister or speaker of the house.
There were 10 Presidents of Congress under the articles before the position was abolished with the adoption of the Constitution:
Samuel Huntington
Thomas McKean
John Hanson
Elias Boudinot
Thomas Mifflin
Richard Henry Lee
John Hancock
Nathaniel Gorham
Arthur St. Clair
Cyrus Griffin
But yes, as a formal singular title designating a head of state, Washington was the first, as the President of Congress was not really the head of the government.
Sort of. Lord President of the Council of State of the Cromwell's England (it existed from 1649 till 1653) could be seen as predating Washington. However, entire Council in corpore was formally head of state, not the Lord President alone.