In this topic..
Recently was reading something interesting. To me at least. In the 1950s and 1960s aliens were thought of as roughly humanoid. After that in sci-fi they were but the educated talked knowledgeably about how unlikely that would be-- that aliens would be utterly, well, alien to us. There would be no reason for them to be anything like us at all.
Recently though there is a counter argument. It rests in the well known phenomenon of "convergent evolution".. that is similar environmental pressures create similar results. For example, dolphins and sharks are far apart on on the evolutionary tree.. but physically are quite similar. The eye has evolved independently many times. As has flight.. and each time in a similar way.
It may be that intelligent life,following the same rules of evolution (some undiscovered) may lead to humanoid type life.. maybe 4 limbs and a large brain plus walking erect are the natural results of certainly evolutionary threads. I think Stephen J. Gould would disagree and I haven't decided my own opinion but it's fun to think that if there is intelligent life out there it might be more similar to us that we might otherwise expect!