The biennial’s biggest surprise comes from an unlikely place: Robert Indiana, an artist who has unfortunately been pigeonholed by a middlebrow public art reputation. This posthumous show does the work to right this wrong, laying out a legacy of radically beautiful and adventurous works beginning with Indiana’s first years in Coenties Slip, a hallowed wisp of history on the docks of what has now been rebranded as New York’s South Street Seaport.