you should read the book
All the characters are interwoven (Mowgli, the wolves, Bagheera, Shere Khan, Kaa, Baloo, the Bandar-Log, etc) and all need to be there - none are incidental to the story.
The Disney version departs from the book significantly, as may be imagined because they were turning it into a childrens' cartoon. King Louie is not in the original book - as said above and several times previously in the thread - he was invented for the animated Disney movie to add humour. It seems they "needed" to retain him for this movie because it is an adaption of the animated one, and so to get around it they made him into a Gigantopithecus which sort of satisfies the general audience because he is still there and also the nerds because they have a better explanation why he is still there (even though it is a major stretch

).
So, read the book.