I have been running Champions for a group of 12-15 year olds at the local church roleplay club. They have had no problems dealing with the mechanics of Champions in gameplay but they are completely overwhelmed about character creation - too much to think about.
My advice is to work on the rules yourself and ask the players what they want to play. The most difficult part is in asking the right questions.
I get all my players to right down (in story form) what they want their character to be able to do and then go away and design all the characters myself. This takes away the intimidation some players feel about the system and takes away the potential of players, who know more about the system, abusing your lack of knowledge.
I then expect to make several re-writes of each character as, during play, players are likely to say "But my hero SHOULD be able to do THAT!" and if I agree then it's time for a re-write - asking them what ability they want to lose - or to make less powerful to allow for the new ability to be added.
Essentially the system is no more than rolling 3D6 for task rolls and a variable number of D6 for effects. Players have to keep track of Endurance, Stun and Body. It's easy to play, the complexity is all in the background and provides you with all kinds of options that may make you, like the rest of us here, convinced that the benefits far outweigh the costs.
Good luck and remember the best piece of advice you've been given is to come back and keep asking questions.