"5 Perkins kites holding up a man at the Harvard Aviation Field, Sept. 1910"
When I saw this photo from the Library of Congress archives posted at Uncertain Times, my first thought was of the Nazca lines, which are described as only appreciable by someone up in the air. I believe there has been speculation that ancient peoples might have used hot air balloons to elevate a designer or project foreman, but certainly the high plains of Peru would be a great place for kite flying.
The Smithsonian archives have one photo of a "human-carrying kite" from 1911. The Wikipedia entry offers very little re human kite-assisted flight: "British Army used kites to haul human lookouts high into the air for observation purposes."