Simplify the following text for a Grade 7 native English-speaking person.
Original: These included many of the musicians who were members of his orchestra , some of whom are considered among the best in jazz in their own right , but it was Ellington who melded them into one of the most well-known jazz orchestral units in the history of jazz .
Simplified: Some of the people who played in Ellington 's band were also famous or important jazz musicians .