Humans as we know them, specifically Homo sapiens, are believed to have appeared around 300,000 years ago. Fossil evidence indicates that early anatomically modern humans evolved in Africa. Over time, they migrated to various parts of the world.
The development of behaviors that define modern humans, such as the use of complex tools, art, and language, took place over tens of thousands of years. By around 70,000 to 50,000 years ago, there is significant evidence of modern human behavior, often referred to as the "Great Leap Forward."
So, if we consider the entirety of Homo sapiens' existence, humans have been walking around in their modern form for about 300,000 years.