ok i know sony has made commercials for the game, and i have to admit it is a great game i played it. But what is the story with them, i mean in real life.

there are wall paintings around showing them, were they considerd gods or protectors of the ancient world

No, not gods.
The wall paintings, just like the collosi, are all fabricated by sony.

collus were a greek myth and they were like a sort of protecter i think

As Gedi said, the only "real" colossus was the Colossus of Rhodes. Looking at general history of colossus it does have its origin in Greece. But it's only gigantic statues, and not a living being, not even according to any myths. The bigger than life-size statues were normally of kings but could also be of gods and private individuals. These statues usually flanked the gates or pylons of temples. Believed to act as intermediaries between men and the gods.

Thus, technically speaking Sony is a bit off with their name "Shadow of the Colossus"... The name means "Shadow of the Giant Stone Statues of dead Kings".... LoL... Nothing about gigantic creatures and battling them...

Well, that's my opinion anyways.

the only USE of the term collosus is for rhodes, but there have been really-big-human-looking things in most mythologies. probably i biproduct of seeing tall people...