Some additional information:
The original title was Jungle Taitei ("Jungle Emperor"), and long before it became anime, it was a manga series (running from 1950 to 1954). Also, the main character's name is "Leo" in the original.
Enthusiastic about the success of the animated version in the USA, Tezuka started to work on a sequel, which would have told of the adventures of Kimba/Leo after he grew up. Only after already doing substantial work on it did he talk to NBC about the project - and got rejected, because the NBC people found his new character designs and plotlines "too dark" and not suitable for children...