Simplify the following text for a Grade 10 native English-speaking person.
Original: Goodallâ s research at Gombe Stream is best known to the scientific community for challenging two long-standing beliefs of the day : that only humans could construct and use tools , and that chimpanzees were vegetarians .
Simplified: Goodallâ s research at Gombe Stream challenged two long-standing beliefs of the day : that only humans could build and use tools , and that chimpanzees were vegetarians .