there are a lot of things to consider. the galactic core is full of nova stars. and a shit ton of radiation. anything that evolved close to the galactic core would mutate rapidly, from the heavy doses of radiation, until they have evolved into something that can deal with it. but they have evolved rapidly. life that formed farther away from sources of radiation would mutate more slowly. i mentioned an article earlier where they were discussing the earths unusually high phosphorous content. phosphorous is apparently formed when novas explode. we were lucky enough that the earth was close to one and got a good dose. that's not a common occurrence.
so, while i am confident that there is life on many other worlds, i'd guess we're around the middle of the developmental scale, some is still swimming and learning to breath that air stuff, and some are travelling the stars at will. but most is slogging through the process of killing themselves, or not. just like us.