Dave, the VS-300 flew in late 1939, and did many trials during the early years. I will ask Sergei Sikorsky if he recalls any shipboard landings or boat/barge landings in that period. I have seen several photos of the test work then, including boat tow and hoist tests, but none specifically of landings, so the Flettner could be first.
Regarding everyman's helo, that can only come when we solve the problem that kills the trained professionals who fly today, probably with computer controlled/stabilized machines where the crew tells the machine where to go, and IT sees terrain, avoids traffic and harsh weather, and lands itself. With the cost of processing today, some micro-modeler will graft his dime sized control system onto a robbie and the solution will be had.
If everyman flew today's aircraft, there would be no need for birth control!