The biggest fiction (constrained by budget obviously) of shows like Star Trek is that most of the intelligent creatures we might possibly meet will look almost exactly like us. I don’t think even the people coming up with Star Wars aliens have the imagination to get it right. They still base it on what we are limited to thinking up as humans and our own likely narrow understanding of what is life and what is intelligence.
The second-biggest fiction is that it would be possible for us to coexist on one planet’s surface considering our needs when it came to gravity, atmospheric pressure and basic atmospheric composition would be very unlikely to be the same.
But that would narrow the scope of a lot of sci-fi, so I let it go.
I always felt that humanoid aliens were also a way to get the audience to more easily emotionally connect and treat them as characters. Its hard to portray a truly alien lifeforms with alien behavior like you would find in a speculative evolution fiction art book while also giving them a human understandable emotionally driven narrative and space age tech for the plot of a story. Its easier to relate to blue cat person than to the Blob I guess is my point.
I really like the comic Humanity Lost for its better representation of alien life in its story. The author really cares about that kind of world building ad im here for it really great stuff.
The amazingly innovative 1930s science fiction author Olaf Stapledon has an invasion from Mars in his epic history of the future of humanity and its various evolutionary stages, Last and First Men. The Martians are a gaseous life form that can come together to sort of form a jellylike mass. They originally think radio signals are Earth’s dominant form of life and everything else is their livestock. That feels much more believable to me in terms of how we would relate to each other.
