it means "History is a way for people who are alive remember people who were still here before they were even born and how the people who are no longer alive helped us get here we would've had a terrible life without them" like for example Martin Luther King Julien, he said black people are equal and other people who ended Slavery
"History is the version of past events that people have decided to agree upon" means that worldwide historians who study the past have agreed on a certain point of view but still have no way of proving it. History as we know it is simply what historians have said to have happened through the evidence we've found, but the real history is completely undiscovered and we have know way of knowing what happened for sure.
