Campagnolo was not the first to market a one piece aluminum hub (shell). There were a number of predecessors, the earliest with which I'm familiar being a Harden model, reportedly dating to 1946.
French manufacturers Prior and Maxi were both producing multi-piece hubs with aluminum barrels mated to aluminum flanges, prior to World War II. There are almost certainly earlier, more obscure examples. In fact, it wouldn't surprise me if there are cases dating back to the mid-1890s. At that time, aluminum was the wonder metal of the bicycle industry. Aluminum frames, rims, saddles and pedals were all availalble in the last decade of the 19th century, so aluminum hubs wouldn't be out of the realm of possibility.