How we cite our quotes:
Quote #1
"If they knew we were here, they would have killed us already."
This is only the second line of the whole film (unless you count the terrified shrieks of the Peruvians with the donkeys), and it stresses how dangerous exploration can be. In a lot of Indy's adventures, "exploration" means "move quietly or hostile locals will kill you."
Quote #2
"Seńor… nobody has come out of there alive!"
Exploration means not just finding a place, but finding a place and returning to talk about it. That probably means stepping over the bodies of the people who came before you. Another favorite adventure movie motif: the explorer walking past the skeletal remains of his unfortunate predecessors.
Quote #3
"The Nazis have discovered Tanis!"
Notice that Indy is stressing a race here. Who gets there first is most important, and the Germans are already ahead of him. We see this a lot in real-world exploration too, such as Cook and Peary's race to the North Pole. Can't we all just share?