Dead Space? can someone explain it to me?

Spoiler?

"How did stupid creatures get the technology to space travel?"

I'm leaving this one well alone

Just look at Americans and NASA, har har.

Disclaimer: NASA are amazing. America is amazing. 'MURICAAAH.

because of the Marker? It transforms life forms to "upgraded" creatures

They not stupid in fact they an ancient race the creatures you fighting are obviously just the pions

Well if you've been following the story the humans created artificial markers everywhere,which is capable of releasing/turning any living/dead humans to poor misunderstood creatures that are just fighting for their independence.. ;)

Go back and play all three games in order.

Not sure if you're being serious or totally trolling us. ^_^'
They're reanimated remains of the people who used to space travel. You know- that's what "zombie" means.

[Spoiler]
It's kinda more complex than that with the Markers and all. Basically some weird ancient tech that for whatever reasons turns dead people into horribly deformed zombies. It doesn't exactly "improve" them as the more fanatic characters claim. It just kills people.
[/Spoiler]

There is probably more to it but I haven't played Dead Space 3, cuz Origin... and too much backlog for the next decade or so to waste my time pirating it.

Read some wiki

you could watch event horizon... it is heavily based off that movie

Play all the games, than your weenie little brain might understand, :3

Atheists have faith there are aliens out in space attacking them (because that would go against the bible), they however are just crazy and it's all in their head (many innocent people where harmed in 9/11)... Dead Space is a story about that aftermath! Joins the USA, freak out and kill anything which moves.

the USG ishimura is a human space ship infested with the alien necromorphs which is more accurately described as an infection or disease
the spire causes a mutation in organics that come within it's proximity
so technically the aliens don't space travel or at least don't use their own tech to do so