Simplify the following text for a Grade 6 native English-speaking person.
Original: On 29 May 1953 at the age of 33 , he and Sherpa mountaineer Tenzing Norgay became the first climbers known to have reached the summit of Mount Everest â `` see Timeline of climbing Mount Everest .
Simplified: Along with Sherpa guide Tenzing Norgay , he was the first successful person to climb Mount Everest on May 29 , 1953 . Mount Everest is the tallest mountain on earth .