Oddly, looking back, it was never the climbing up that was scary. Our mother always said we learned to climb before we learned to walk. It was only after I got on the beam and could see all the way to the floor that it was scary. Anyway, that barn provided the perfect platform for every sort of imagination game. The beams could be the yardarms of a sailing ship, The walls could be the flanks of Mount Everest. We built forts and caves and cabins using the bales of hay and vanquished our enemies all day long. We often became characters from books, movies, or TV shows; Roy Rogers "the King of the Cowboys" was always a favorite. Cowboy heroes were very big with boys of my generation and Hollywood gave us a good supply of them. They were "knights of the Old West" with pure hearts and iron courage, and we in our innocence believed in them. I'm not sure it's a good thing that today's kids are so much less naive.
Because we lived in semi isolation out in the country, my brother and I usually had to provide our own entertainment. We didn't have a gang of kids around to play with. We never thought about this, it was just the way it was. Sports and games were things we did at school. At home all play involved imagination even if it was playing an imaginary baseball game (at least I always won!) To this day, I seem more comfortable in solitude than most people I know.