It’s an image of a man in thoughtful repose, looking down at the camera as he stands in front of a brick wall. In short, a selfie that seems designed not to call too much attention to itself. And yet, it’s the picture that some say may have played an important role in the fight for racial justice. This is, of course, the now iconic photo of George Floyd — arguably the most widely distributed image of the man whose May 25, 2020 murder by former Minneapolis police officer Derek Chauvin sparked a wave of protests throughout the country. The...