If you had suggested three or four decades ago that Jerry Lee Lewis would be the last living artist among the stars of Sun Records — almost among all rock ‘n’ roll stars of the 1950s, for that matter — you would have been laughed out of the room. This, after all, is the man whose drinking, drugging, philandering and violent outbursts were the most epic in rock ‘n’ roll. Yet at the end of October 2014, the Killer was not only still alive, but he was seemingly everywhere: He had two new albums out, a superb authorized biography by Rick Bragg, profiles in countless other media, sitting in with Paul Shaffer’s band on Late Show with David Letterman. Yet the 79-year-old Lewis, on TV and in concert, is hardly the wiry stick of leering danger, braggadocio and pure energy most of us remember; his face and body are now puffed up, and his gleefully malevolent manner has turned friendly, agreeable. He can’t seem to stop smiling. Lewis, formerly Public Enemy No. 1, has become an all-American hero. Still, his greatness as a singer, piano pounder and American song interpreter is barely diminished.