RAIDERS OF THE LOST ARK is just another entry in the long list of things that prove that letting George Lucas have a good idea and then giving it to somebody else is the best way to make something awesome. Letting him have too much freedom with it, as we all know, leads to some terrible, horrible, no good, very bad things.
But when it comes to inventing clever characters and iconic story elements, he's pretty amazing. I think his main problem is just that when he has too much freedom he tries to include every stupid little idea that he has, thinking that each one is going to be something timeless. Instead we end up more "You don't want to sell me deathsticks" and less "You will never see a more wretched hive of scum and villainy".
There was a brainstorming session between George Lucas, Steven Spielberg, and Larry Kasdan, in which they just sat around bullshitting together, spitballing ideas back and forth, and they basically just created the entire movie out of nothing. If you don't want to read the entire 90-page transcript, trust me when I say that it's actually pretty amazing to read these guys, some of the most creative cinematic minds ever (no matter how much shit I talk about George Lucas), just sit down and talk about a vague idea they have and turn it into one of the greatest characters in the history of film. They just say shit like, "The other thing we've added to him, which may be fun, is a bull whip." It's one of the most signature aspects of the character—when you think Indiana Jones, you think bull whip—and it's something that George Lucas just came up with out of nowhere, and brought up out of the blue.
And Steven Spielberg comes up with the famous boulder scene. They were talking about how they were going to introduce the character, and they decided to have him in a temple trying to get "the thing" (because even then they knew that whatever he's chasing doesn't matter), and Speilberg just interjects with, "I have a great idea... There is a sixty-five foot boulder that's... coming right at him. And... he gets to outrun the boulder."
I imagine these three dudes just chilling out with a few beers, shooting the shit, and it turning into one of the best and highest-grossing movies ever. When was the last time you and your friends talked about your "amazing ideas" that turned out to be anything but worthless?
It's a good thing George Lucas hired Harrison Ford to redo his cabinets, because that's how the mostly-carpenter-and-sometimes-actor got his big break (I think that's how Jesus got started too), being cast in Lucas's AMERICAN GRAFFITI and then eventually STAR WARS and RAIDERS OF THE LOST ARK (duh). Actually, Lucas hired Ford to read lines while other actors were auditioning, and his portrayal of Han Solo was so perfect (because he is Han Solo) that he got the role. And Lucas, having already worked with Ford in the past, decided to have Indiana Jones played by... Tom Selleck. Really. It was Spielberg who wanted Ford from the start, and Lucas eventually relented, only after Tom Selleck wasn't able to accept the role.
The plot of the movie follows Indiana Jones as he appears to prevent the Nazis from opening the Ark of the Covenant and turning the tide of World War II (the TERMINATOR 2 of World Wars), but actually leads the Nazis right to it and only "wins" because God intervenes and saves the day. It is the most literal deus ex machina pretty much ever. Seriously—without Jones, the Nazis wouldn't know how long the Staff of Ra needed to be. The Nazi bad guy, Arnold Toht, burns the headpiece into his hand, but it doesn't have the complete information. Jones, in his attempt to get to the Ark before the Nazis do, builds the Staff in the correct length, and they just follow him to it. He could have just stayed in Nepal with Marion, banging her brains out, while the Nazis spent the entire war wasting time, money, and resources digging in the wrong spot for a "superweapon" they weren't even sure existed.
Jones fucked up by leading the Nazis to the Ark. But he obviously knows what happens when you open the Ark, because he tells Marion to close her eyes when the Nazis do it. So the question is, why didn't he just let the Nazis take the Ark to Berlin? Or better yet, help them—he has no qualms against pretending to be a Nazi, because in the series he dresses as one about fifteen times, and he could have made them pay him a bunch of money, bring the Ark to Berlin, open it in front of Hitler, and end the war in about thirty seconds. My theory? It was all so this scene could happen in the sequel.