Here’s a very in-depth history and introduction to jazz guitar. Great for metalheads and other types of guitarists!
I caught the ‘jazz bug’ after listening to some jazz-rock fusion such as Greg Howe and Scott Henderson. So that might be a good transition style for you if you currently like rock or metal. Then when I started to learn how the chord changes work and how to improvise over key changes (I was used to soloing in one key) I really got into this stuff. So I started listening to jazz guitarists, sax players, trumpet and piano players to name a few.
Here’s a Jazz Guitar Greats DVD I bought showing many video performances of jazz guitarists such as Wes Montgomery, Joe Pass and Barney Kessel.