When one starts the terran campaign, it is known that this thing is a race very similar to humans. the terran campaign is a man with a powerful looking battle armour.
We learn in the briefing that they are futuristic and have very advanced robot technology and that the character we play is a commander whose identity is not and will not be learned.
We see that the scv and marine are suave technologically advanced machines but that they are, humorously, piloted by versions of recognizable American who may or may not agree with the happenings of those making the decisions of their fate, the commanders. The scv is a man who seems to have a relaxed, urban manner, like a 9-5 fork lift driver who likes his coffee and beer with the game but gets yanked into situations adventurous enough to make him quesy. The marine is the classic pop-culture sergent type from the movies, not to be fucked with in any circumstance.
The console hologram, technological robot lady identifies the terran as an interplanetary species. Chau Sara and Mar Sara are two planets from the same solar system and the commander must be brought there to save them from the zerg. We do not know why the zerg are hostile to the humans. It is pretty much second nature to assume that it is just some instinctually predatory species that can travel in outer space.
James Raynor is a marshal who likes to save people. He’s a hero type guy who does not like to let other humans innocently die to the zerg. The “Confederates” who are the most powerful government in this terran sector, contrastingly do not care about interests besides their own meaning they forsake civilian terrans. The representative of the confederates is general duke. A man with a cowboy, souther drawl, major corporation vice president, detached, tobacco addicted vibe. We meet Edmund Duke because he is always disrupting Jim’s plans to save people in the interest of the dominating confederacy.
Jim Raynor is contacted by Arcturus Megsk who is from another planet that is terran which we learn has been nuked by the confederacy, Korhal. Arcturus Mengsk has almost a royal king like demeanor and always gets his way. Jim becomes his ally because more innocent people can be saved from the confederacy this way. One of Arcturus’ greatest agents is Sara Kerrigan who is a ghost, which is a tactical high tech terran unit. She is a hero ghost, to boot, meaning she is even better than the average ghost.
Sara Kerrigan is a very attractive woman. Her hair is red and her persona amplifies the mind of a hardworking individual. She believes in the well being of the terran race. She is psychicly gifted and that is why her brain is implanted with psi emitters by dominion researches. The goal is to destroy other terran planets for more power but use the zerg as a way to cover up the blood on confederate hands.
The psi emitters in sara kerrigans brain attract the zerg, hence sara kerrigan is unwittingly the cause of the zerg attack on the terran sector. Unfortunately, just as the zerg cannot resist the attraction of psi in their brain, sara Kerrigan cannot resist the temptation to blindly follow those who she owes favours. A product of a good nature gone wrong. Jim Raynor can see that Mengsk is ruthlessly power hungry and untrustworthy but sara Kerrigan is too loyal to see this.
General Arcturus Megsk, has made it his goal to rule the sector and will stop at nothing. He uses the psi emitting technology to attract the zerg to mar sara and destroys the confederacy. The protoss seem to dislike zerg though and they are here to stop the zerg. Megsk sends Kerrigan down to stop the protoss from halting the zerg aggression on Korhal but when she has done so she is left for the zerg.
So the terran sector is destroyed but Mengsk has what he wants- he can control of everything terran.
From the fireblazing smoker who kills the organic in the name of a relaxing barbecue to the tactical evasive ghosts who bypass enemy anti air to launch nuclear strikes on enemy planets, to the suave Russian generals precisely commanding massive metal cities between planets, the terran have great survivability in the cosmos, and many quirks to make it interesting. The terran campaign seems to ask, do the means justify the ends?
The luxurious ships and the power to destroy and dominate with powerful machines but how far has the human experience come? Not far at all because the ends cannot justify the means.
Mengsk starts out with reasons to destroy the confederacy but the desire to be at the top of the whole enterprise makes him stop at nothing for this goal. He has no care for Sara Kerrigan as a person besides what she can do for him.
Sara Kerrigan is loyal and willing to work for the betterment of others but she chooses the wrong ally. She is loyal to the old ideals of the dominion as much as it destroys her.
Jim who can see through the stupidity of all of it is left with no other allies potent enough to stop the doom that Mengsk spells for the outcome of the terran.