The original Jungle Cruise attraction that mixed together ideas from Oscar-winning wildlife documentaries, a Humphrey Bogart-Katherine Hepburn film and “20,000 Leagues Under the Sea” lacked one thing Walt Disney really wanted: Live lions, tigers and giraffes.

“Walt did originally want to have real animals in the Jungle Cruise,” Imagineer Vanessa Hunt said in a new Disney+ series. “It was quickly discovered that would lead to a not very exciting trip for our guests. Animals like to sleep a lot during the day.”

Walt Disney Imagineering takes a behind-the-scenes look at Disneyland’s Jungle Cruise ride in the new 10-episode “Behind the Attraction” series debuting on Disney+ on Wednesday, July 21.

The first five episodes dropping on Wednesday focus on Jungle Cruise, Star Tours, Haunted Mansion, Space Mountain and Twilight Zone Tower of Terror/Guardians of the Galaxy — Mission: Breakout. Future episodes will feature It’s a Small World, Hall of Presidents/Great Moments with Mr. Lincoln, Disneyland Hotel, Disney theme park castles and Disney trains and monorails.

The original concept for the Jungle Cruise drew inspiration from True-Life Adventures — a wildlife documentary film series from the 1940s and ’50s that won Disney eight Academy Awards. The ride concept later morphed into a travelogue version of the 1951 Bogart-Hepburn adventure film “The African Queen” taking riders on a tour of exotic waterways of the world.

Theme park design was decidedly low-tech in the mid-1950s. Disney Legend Harper Goff used a stick to trace the outline of one bank of the river and then moved 15 feet to the other side and drew the other bank so a bulldozer could dig the trench for the Jungle Cruise.

A major challenge facing Imagineers building the Jungle Cruise was turning an Anaheim orange grove into a lush jungle.

Disney Legend and landscape architect Bill Evans canvassed Anaheim neighborhoods buying trees from residents for the Jungle Cruise and Adventureland. When that avenue was exhausted, Evans salvaged trees from the ever-expanding Santa Monica, Pomona and Santa Ana freeways. Orange trees from the Disneyland property were planted upside down along the banks of the Jungle Cruise because the roots looked like exotic trees.

The “20,000 Leagues Under the Sea” special effects team that created the film’s giant squid was recruited to build audio-animatronic animals to replace the real-life wildlife Disney had initially wanted for the Jungle Cruise.

The attraction’s famed “backside of water” — Schweitzer Falls — serves as a natural mixer to disperse the murky green dye that’s added to the Jungle Cruise water to hide the animatronic mechanics just below the surface.

The Jungle Cruise began with the skippers delivering a rather dry documentary-style recitation of facts about the rivers of the world — before a bold dash of dry humor was added to the script.

“The Jungle Cruise we know today is not the Jungle Cruise that we opened with,” Imagineer Jeanette Lomboy said in the Disney+ episode. “Walt actually wanted Jungle Cruise to be more serious.”

Walt Disney initiated a major makeover of the Jungle Cruise in 1960 after he overheard a mom in the park say she didn’t want to go on the ride again because she had been on it before. That wouldn’t do. Disney Legend and chief gag man Marc Davis was brought in to introduce some humor and repeatability to the then 5-year-old attraction.

Davis added a slew of dad jokes to the skipper script and comic scenes to the jungle featuring apes, hyenas and native tribes people — including some gags the Disney+ show acknowledges were based on “stereotypes now recognized as inappropriate.”

Curiously, the Jungle Cruise episode of “Behind the Attraction” shows none of the recent changes made to the ride to remove racist stereotypes — but it does find plenty of time to promote the new “Jungle Cruise” movie starring Dwayne “The Rock” Johnson as a riverboat skipper and Emily Blunt as an intrepid explorer.

The “Behind the Attraction” episode ends by making a connection between the Jungle Cruise attraction that debuted at Disneyland in 1955 and Disney’s Animal Kingdom theme park that opened in Florida in 1998.