I’m wondering if it’s pseudo religious with humans being created in God’s image (Ancient Aliens stuff), the human-centric idea that intelligent life must resemble us, it being easy to make costumes for movies and TV when all you need to do is paint someone’s skin, or if SciFi writers were going for the uncanny valley effect for example.
Exactly. The thought that extra terrestrial life we’d come in contact with would be in the form of one life from piloting a spacecraft is, in and of itself, such a human concept.
Let alone a humanoid life form.