First at that age you will almost exclusively face zone defenses. So while it is great to have a guy that can break defenses down, passing is the bigger key on offense. By that age players should be able to make a variety of types of passes, if they don't this should be highly stressed during practices.
Next you need to develop other ball handlers. At that age a good team will score 30% of the time in the half court (by your question you don't have a good team and will probably score 15-20%). Being able to push the ball up the floor to get easy buckets is the key to winning. Which means making sure everyone on your team can make a layup running at 80-90% and that they understand how to outlet quickly and run a simple 3 man attack going up the floor. Full court 3-2 drills really help with this.
You don't want your star player always bringing the ball up because you want him on the floor 80-90% of the game. This will have to be on a case by case basis. Any game/situation where others can bring it up without having the ball stolen from them, do it. Over time a few players will stick out and learn to handle the ball.
On offense it is really basic. Everyone is moving, picks are being set liberally, there are no positions. The worst thing you can do as a coach is call one guy your center, two your forwards, and two your guards and they sit like robots at their spots on the floor. Even worse is having 2-3 kids constantly a few feet behind the 3 point line that can't hit one. The defense will eventually cave in and then you are playing 3-5 with your star getting doubled/tripled constantly.
Your star will inevitably be doubled all game but the goal is to have enough movement to confuse the double teams so that you can open up a guy right under the basket. Really you should have kids rotating everywhere but the key points are the weakside under rim and the free throw line. The end goal is your star has the ball around free throw line and other players are moving. The guy guarding him gets beat and then the bottom zone guy helps, the other side of the zone should rotate and then another player opens low.
You have to realize that your star player will either score or setup 70%+ of your baskets. However he doesn't have to dominate the ball. Make sure your players understand you want low risk and quick passes. Make sure they understand there is no shot clock and a bad shot will mean riding the bench for a few minutes.
That is the last thing I will mention. Take a kid out if they do something dumb or if they aren't hustling. Taking bad shots is a virus that spreads quickly on a mediocre kids rec team. I often hear dads yelling at their kids to shoot or get theirs. By simply benching a kid after every bad shot (something clearly out of range, incredibly bad technique, or with a defender right on top of them from outside) you set a precedence that the team will adapt to very quickly. And yes you have to treat your star player just like every other kid when it comes to this. Your star player will have off games and if he is jacking up bad long twos because he thinks he needs to beat some clock, then so will everyone else and the 10 point game turns into 30 real quick.
Note I have two rules for my guys bringing the ball up at that age:
If you bring the ball up you must dribble inside three point line unless getting trapped before making a pass. This keeps from fighting over bringing it up and making the lazy wing pass which is my pet peeve at that age - since it puts offense in worse position and if it gets stolen always leads to fast break. The longer you have the ball the more chance for a turnover so I want my PG (for that play) penetrating and forcing the D out of position.
My PG (for that play) can not take any shot until two other players touch the ball except for a layup. A wide open 3 would get him benched. Again this keeps the kids who are only worried about scoring from begging for the ball every possession.
Basically all the advise I am giving you is for that age group. I would not use that for varsity level high school or college. It is also aggressive. But only aggressive in a way where I would want players to put themselves in position to get a very easy basket and possibly a quick turnover vs. pass the ball around 10 times behind the 3 point line and possibly turn the ball over.
