Simplify the following text for a Grade 6 native English-speaking person.
Original: As the first black man to play in the major leagues since the 1880s , he was instrumental in bringing an end to racial segregation in professional baseball , which had relegated black players to the Negro leagues for six decades .
Simplified: He was the first black man to openly play in the major leagues since the 1880s . He had a big role in bringing an end to racial segregation in professional baseball .