The original Jungle Cruise concept was drawn up Disney Legend Harper Goff as seen in this artwork.
The attraction’s concept, including the ride vehicles, was influenced by the movie The African Queen starring Humphrey Bogart and Katharine Hepburn, which was released a few year before the park opened in 1951.
The initial idea for the ride involved a big lake with an island in the middle full of tropical scenery and foliage that the boats would circle. Goff explained to Walt why that wouldn’t work:
“What you’ve got is everybody on that boat, if you go counterclockwise around the island, having to look to the left. The boat isn’t going to go sideways, so half the people will have to look over the shoulders of people beside them.”
Goff then suggested the island have a river run through it that the boats could enter. Ultimately, Goff and Walt realized the length of time it would take to cross the lake was problematic, so Goff started over with a closed loop river concept.
Goff also explained in a 1973 interview with Bob Thomas, the author of Walt Disney: An American Original, that early on Walt wanted the boats to be automatic:
“On the Jungle Cruise ride Walt didn’t want any pilots in the boats. I thought that if people were alone with some gas engines they might panic and things would go wrong. I wanted a man on board: Going on the adventure with him would add to the thrill and he would keep kids’ hands out of the water. Walt found out that the human touch was important.”