Where I talk to you about linguistics and anthropology, science fiction and fantasy, point of view, grammar geekiness, and all of the fascinating permutations thereof...
I'm glad the pulp "aggressive monsters from space" angle is becoming less common. It seems egotistical to think that other sentient life will obviously want to attack us for our valuable ...whatever it is they want. Although other sentient lifeforms could have the same negative traits as colonial humans, it's much more fair to consider all the possibilities and acknowledge that there's a lot we don't know.
I like the analysis there. Not just that humans aren't the only possible model (like for example the dolphins you mentioned before?) but that humanity itself is slowly moving past the ruthless aggression. The evidence suggests that no successful space program will survive an aggressive species as well, so if they managed to get off planet, there needs to be something uniting them at least.
I think humans anthropomorphize basically everything. Which is great and all, but seriously, the options are wide open. I agree with both of you. And Margaret, you make a good point that getting into space is very challenging and requires a lot of united resources.
I think "good" and "bad" aliens have an equal chance to exist just as there are "good" and "bad" humans. I think that's why Babylon 5 has appealed to me for so long. The aliens all had their own agendas and sometimes those agendas clashed, sometimes they didn't. Sometimes it was humans vs humans while the aliens watched. But in the end, the genetics didn't matter, only the choices made and the acceptance of the consequences.