Hillary and Norgay climbed Everest first. When climbers climbed a peak like Everest they would leave something at the summit, like a flag or something to prove they were there. Nothing was found on the summit from any previous expedition by Hillary and Norgay. I suppose wind and weather might have taken away anything that was left, but as the man said, " you have to get back safe and sound" or the climb wasn't finished.
There are a 175 bodies of dead climbers on Everest.