A Black Man John Hanson was the first President of the United States in 1781 why is he not mentioned as the first president of the USA?

John Hanson was the third President of Congress under the Articles of Confederation, but the first one to complete a full 1-year term. The Articles had no executive branch nor a judicial system. He was of English/Swedish heritage. He was not black. His grandfather came to the colonies as an indentured servant, not as a slave.