The answer to your question is yes, the humor FDR used for this speech was effective.  Because the speech was given at the laying of the cornerstone of the library which would house his presidential papers, his humor was to lighten the mood and use a bit of self deprecating humor to make him a realistic man, not a distant president.  The part at the beginning of the speech about the small boy who sailed toy boats he made and dug holes for prairie dogs where some of the guests were sitting made him approachable.  The momentous idea of this library became a place where scholars could do research just as at any other library.  FDR made the people listening laugh which would be hard to do because the papers usually would arrive at the library only after his death.