That depends... Do you mean the first head of state titled as president or first person called president? The word traces to praesident which itself comes from praesidēre, the former meaning "governer/ruler" and the latter meaning "to rule over a group" (i.e. to preside), both Latin. It made its way through old French and by the mid 15th century arrived in English as president. The English took ahold of it in a governmental capacity in reference to the leader of a council, such as President of the Privy Council, during the Commonwealth era - but again this word was synonymous with our current use of "chairman" as they were simply the leader of a board or group. The French likewise used it to mean those who preside, attaching it to their magistrates.

The first president in America by that title was Edward Wingfield who was named president of the council upon landing at Jamestown in May of 1607. Later, just after the revolution, some states began to title their cheif magistrate as president such as Pennsylvania. Still, these titles designated men that ruled or presided over executive councils and not as chief executives of the state. The Continental Congress even elected a presiding officer, first selecting Peyton Randolph. Numerous men held this post and Washington was even chosen as the President of the Constitutional Convention. Yet again, he presided over the Congress of the States, not the States themselves. It wasn't until the United States Constitution was signed that we came to define president as a chief executive, and that was the first time a ruler of a nation was denoted as a president.

For more on the Senate debate about using the President as the formal title, check out this [previous answer] (https://www.reddit.com/r/AskHistorians/comments/hhnwds/ive_heard_that_the_title_president_wasnt_the_only/) I gave about that.

For how Washington defined what a President by modern terms does, which in turn inspired the rest of the world to emulate his lead, check out this [previous answer] (https://www.reddit.com/r/AskHistorians/comments/gkqd62/people_think_of_george_washington_mostly_known/) I gave about that.