I feel you missed my point entirely... or you may be a troll. Anyway, behold a wall of text!
Lets take this picture:
http://s1240.photobucket.com/user/betterduckjmg/media/Screenshot2012-03-26at13341PM.png.html
Forget the movie, the opening scene. Imagine you see this for the first time. This is a guy pointing to 6 circles, with some guys in the background. Nothing more.
How do you fill the void between "a drawing of a guy pointing to 6 circles, with some guys in the background" to "a bunch of people worshiping an engineer, our creators, who is pointing to the system he came from".
Even taking into account that the star system is not visible by the naked eye, or without state of the art telescopes, how do you conclude that they were our creators?!? i would find perfectly reasonable to assume that we were visited by aliens, and that it was an invitation, but assuming outright that the visitors were our creators is just ludicrous.
Shaw's interpretation of the drawings seems the sort of interpretation that pseudo archaeologists and guys from Ancient Aliens make from stuff that already have reasonable explanations. And I'm supposed to suspend by disbelief enough to believe that an Ancient Aliens guy would convince some multi gazilionaire to fund a journey across space and time to meet the so called "engineers". And yet she has the nerve to justify her conclusion to fellow scientists with "that's what I choose to believe". This is not science fiction, this is fantasy fiction.
Why would they want to seem threatening?
Again, you missed my point.
This is not a date. This is not a scheduled meeting. They were not invited. There was no direct communication between the two parties prior to this meeting. Calling it a meeting assumes that there's a second party. That second party's presence is being assumed based on .... "that's what i choose to believe.".
They didn't have any idea of what they would find. This is my point! They could find engineers, t-rexes with laser beams attached to their heads, or nothing at all. I don't care if you're a peaceful person or not, you WOULD take the necessary precaution. Like I said, there was no preliminary exploration to the derelict.
And Shaw has no say in the matter anyway, isn't she just a "scientific" consultant? There's a mission captain and a ship captain, unless she also wants to pilot the ship with "what she wants to believe".
It all boils down to game theory. Best case scenario, you're meeting your creators who are so advanced technologically that a flame thrower would look like a water pistol to them. Worst case scenario, you're meeting some t-rexes with laser beams ... hell even in this case the flame throwers look silly.
I don't think after 15 seconds you'd realize you couldn't breath
Maybe, maybe not. They do say that, by chemical analysis, the air is breathable ... but there may exist some sort of airborne organism. Shaw expresses that concern further in the movie as a probable cause for his douche boyfriend's demise. An airborne organism could have immediate repercussions, or it could take more time. For instance, pulmonary anthrax can take SIX DAYS to incubate. SIX DAYS.
