Raiders of the Lost Ark argument makes no sense

Amy ruins Raiders of the lost Ark by saying:

Amy: "Indiana Jones plays no role in the outcome of the story. If he weren't in the film, it would turn out exactly the same."

And it everyone thinks Amy is correct. But Howard provided two counterarguments that were dismissed as incorrect, but they were actually correct:

Howard: "The Nazis were digging in the wrong place. The only reason they got the ark was because Indy found it first."

Leonard: "Actually, they were only digging in the wrong place because Indy had the medallion. Without him, they would've had the medallion and dug in the right place."

Howard: "If it wasn't for Indiana Jones, the ark would never have ended up at the warehouse."

Leonard: "Although technically Indy was supposed to take the ark to a museum to be studied, he couldn't even get that done."

So Leonard was saying Howard's arguments did not prove that Indy was a hero, and that is correct. However, Amy wasn't arguing that, she was arguing Indy had no impact on the story, but Leonard proved he clearly did have an impact on the story.