Regarding Russell's offense there is something that people need to know. Russell was the 3rd, 4th or even 5th offensive option on most of the teams he played on. Heinsohn, Cousy, Sam Jones, Bill Sharman, Frank Ramsey, and Havlicek were all offensive options that came before Russell.
Also, for many of those teams, Russell was playing 44-46 MPG whereas the next player in minutes was around 30-36 MPG. The reason is because of Auerbach's system in which defense and fast break basketball ruled the day and he needed Russell playing huge minutes to anchor the defense and start the fast break with rebounding and outlet passing.
Also, regarding Russell's FG%, let's remember that in those days there was no three point line to spread defenses out and give big men room to work. The game was much more physical to the point where people would get into fights on a near weekly basis and never get thrown out of the game.
That all means major hacking and pushing and elbowing and punching when big men went up to shoot. It meant a lot more people around to do that since offenses always tried to push the ball inside and defenses stayed in tight. A long shot was a 17 footer.
All big man FG%s were down in those days as compared to now due to the rules changes.
Lastly, Bill Russell might have been the smartest basketball player ever. Why did Wilt post such big numbers on Russell at times? because he demanded his team get him the ball every time and because Russell always let Wilt get his points and rebounds early while Russell coasted so that Russell would be able to have the energy to outplay him in 4th quarters to win games. Wilt was all about numbers. Russell was all about winning. Russell didn't care how much Wilt scored from the 1st-3rd quarters just so long as he could shut him down in the 4th quarter and the Celtics could win, which they did over and over and over again.
Why people are so quick to crown a 6'6" modern day era player as being able to do anything in the game and change the game and be the best player ever but overlook the fact that a 6'9" older era player couldn't do those same things and change a game and be the best player ever astounds me.
Heinsohn, Auerbach, Cousy, just about any Celtic has said it 1000 times. If Russell wanted to average 50 points a game he could have. If he wanted to average 40 rebounds a game he could have. He chose not to because it wasn't in the best interest of his TEAM.
Russell didn't lack offensive skill. He just didn't use the skills he had to their fullest because it wasn't in the best interest of his team winning. His playing unreal defense, rebounding like a fiend and making excellent outlet passes were in that team's best interest and 11 titles says he made the right decision.