"The idea for JarJar Blinks is to take the annoyingness of Barney and Adam Sanders comical abilities, add it with Snarf from Thundercats and a combied SpongeBob with that crazying looking guy. Then subract Scrappy Doos with that funny looking dude in the glassess. All this togethers makes JarJar the tag along character we need to push the story forward. Hell, look how well Yoda turned out and he is the cross of Kermit and Miss Piggy! You know what! Just make the damn thing happen or you're all out of a job."
That is the only way Lucas could have got a god awful character into the story. All he does is push the plot along, hell, thanks to Jar Jar the Republic falls.