Jar Jar was useless to the movie. Oh, he leads the two Jedi to the Gungans, who loan them a sub to go to Theed. Most of which was filler, really. It was like the KING KONG remake taking 45 minutes to get to Skull Island...we all know they are going to get to the island...they have to, or no big gorilla.
Qui-Gon Jin may have been an unneeded character. Make a full fledged knight Obi-Wan find Anakin, and thus he bears the great blame for the Republic's fall. Proof in point how unneeded two Jedi were....while Qui-Gon is in Mos Espa....Obi-Wan does almost nothing for all that time. It would be like having ANH character who stays on the Falcon the whole time they are on the Death Star.
This all belongs in another forum.