Growing up with jazz, I had very helpful buddies guide me thru playing any parts I found complex. I feel I can navigate anything now as a result. It's never too late to start..... Dummies guide to Jazz.... Most of the chords in jazz are simply familiar patterns and familiar exceptions/variations to those patterns. Instead of thinking scales or key, I've always thought in terms of a "pool of note choices" that will work with that chord or group of chords (chord progression). I've found thinking "add this note", "change this note", and "try to avoid this note (unless it sounds good)" vey helpful - it opens your ear & your playing tremendously. My brother can play anything on guitar/dobro/mandolin, but cant explain note choices other than "it sounded good". As Chris stated, at the end of the day that's what really matters.