Joshua Kosman May 14, 2021Updated: May 14, 2021, 11:57 am Pianist Jeremy Denk leads the San Francisco Symphony from the keyboard at Davies Symphony Hall. Photo: Kristen Loken One outcome of the COVID-19 pandemic that some of us dared to hope for was a re-examination of artistic priorities in concert life — in particular, a deadening reliance on the same small set of certified “masterpieces.” What if the emergence from the shutdown offered an opportunity to allow more diverse voices into the conversation? Well, it’s still early days, but there are signs that might be coming to pass. The San Francisco Symphony gave its first live concert before a ticket-buying public on Thursday, May 13, an intimate affair led from the keyboard by pianist Jeremy Denk. And the first music to be heard was by William Grant Still, one of the leading figures in African American classical music and a woefully underrepresented name in concert life.