I’ll just continue spitballing ideas here:
Qui-Gon sacrifices himself to defeat Maul. Show him push a button on Maul’s wrist the moment he gets stabbed, that activates the ray-shield, so that Obi-Wan can take a free hit on Maul, either killing him instantly or gaining a winning advantage.
Or let Obi-Wan take the other half of Maul’s lightsaber to cut him in half. Him using a red blade to take revenge would be a great detail and pretty easy to do. Just change the color of the blade and replace the close up of qui-Gons saber.
Use some material from the Gungan battle for a prologue.
Have the Droid army go against the Gungan before the movie starts and introduce Jar Jar as a leader type of character, who ran away. Make Him Boss Ness’ son maybe, to explain why he was in this position in the first place. He would now not be a baffoon, but a coward, who wants to redeem himself. So he chooses to guide Qui-Gon and Obi-Wan to the Gungan, without hesitation and chooses to take the dangerous path through the core to save time. This would build up to the moment he convinces Amidala to go back and fight.