John Hanson was born in Charles County, Maryland in 1715 and died in Oxen Hills, Prince George County, Maryland on November 22, 1783. There is much debate about John Hanson's ancestry with one camp claiming he was descended from Swedish Royalty while the other group claiming he was a Moor. Neither of the assertions have merit.
Source: johnhanson.net
Specific myths
First president
The most common myth about Hanson was that he was the first President of the United States.
The origin of the claim that Hanson is the "forgotten" first President stems from a 1932 book by Seymour Wemyss Smith titled John Hanson – Our First President. Officially Hanson was the third President of the Continental Congress, successor to the first two men to hold the office, Samuel Huntington and Thomas McKean. He was the first to serve a full one-year term, and the first to formally use the title President of the United States in Congress Assembled.
The office of the President of the United States in Congress Assembled was, despite the name, not an executive post. It bears a closer resemblance to the modern Speaker of the United States House of Representatives or Vice President of the United States. The office was in existence from 1781 to 1788, under the Articles of Confederation. It was replaced by the modern office of President of the United States when the Constitution took effect in 1789. The modern office is significantly more powerful as an executive position.
Hanson was of African descent
Dick Gregory, comedian and African-American activist, publishes an on-line column called Global Watch. In one of his columns he repeated most of the myths and added a new one, that John Hanson was the descendant of an African American slave.
There are two possible origins for this belief. The first is that Hanson's grandfather, another John Hanson, was an early English immigrant to Maryland. As was common at the time, he worked as an indentured servant on his arrival in the New World to pay off the cost of his passage. In 1661, his first master, William Plumley, sold his contract to Edward Keene and recorded the contract with the court of Calvert County, Maryland; similar court records were also used to transfer title to land and slaves. But, in six years, the immigrant John Hanson had worked his way out of debt. A few years later, he purchased his own small farm. There is no record that the grandfather was black, but the record of sale of the indenture contract may have been confused by researchers with that of chattel slavery.
Another alternative may be a simple case of confusion with Senator John Hanson, a politician from Liberia, who was involved with the resettlement of freed slaves in that country. Whilst this Hanson was indeed black, he lived a hundred years too late to be an ancestor of Hanson of the Continental Congress.
Source: wikipedia.org/wiki/John_Hanson_(myths)