Lots of people were way more important than history books give them credit for. Do you have a favorite?
Mine are Ibn al-Haytham and Mansa Musa. For very different reasons. Ibn al-Haytham basically invented the scientific method. And Mansa Musa was such a baller that he caused inflation when he visited places.
The biggest for me is not a person but a group. The people who settled the islands of the pacific.