You know, of all the slang, that's the one I'm actually surprised you don't know.

I'm a skill monkey. Its the jack of all trades, master of none type, or at least not master of much. Able to do a bunch of things in a passable way, but not the best of the best for the job. [Like taking over lockpicking when the locksmith is in the hospital.]

Unless you've had centuries of practice and then you can be an expert in many things, but basically prioritize range over expertise.