I finally sold my guitar on Craigslist the same day I finally saw “School of Rock” (2003). I don’t know if that’s ironic or just a coincidence. I also don’t know if “School of Rock” is good because of, or in spite of, Jack Black. His spazzy histrionics are a tiring distraction. However, his background as an actual musician provided authenticity in a way that a Chris Farley couldn’t have been able to 10 years earlier or a Zach Galifianakis wouldn’t be able to 10 years later. It’s the starring role Black was born to play. Probably the only one.