It seems absurd to ask, but who was Benjamin Franklin, really? The American founder’s legacy is at once ubiquitous and somehow elusive. He was never president, nor a cabinet secretary—he’s not even name-checked in Hamilton. Surveying his various careers as a scientist, inventor, writer, publisher, and diplomat, one could be forgiven for not properly engaging with any of them. Call it the curse of the polymath. That was the challenge before filmmaker Ken Burns, whose new, two-part documentary, Benjamin Franklin, premiered April 4, 2022 on PBS. The famed documentarian spoke…