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.