Richest man in history and already unknown to most of the world, along with many others on the list. Just goes to show that legacy is not measured on a balance sheet.
Another lesson - there is no one legacy, we each have our own context. Go overseas and they will know Mansa Musa better than our local legends. Sort of like you comparing your high school music playlist with a friend in college from another country and you're like...woah...never heard of these artists!