I remember a teacher worrying what effect extra-terrestrial characters could have on children as they often assciate themselves with them.

My answer was: well, they all look so human anyway it's indeed with human characters they will be associated with in the child's psyche.
It's like teddy bears, or the characters in Mother Goose tales:-)

In a way, it shows the failure of being able to describe extra-terrestrials.
They so often look so much like us. Why bother with SF stories if it's like that?
Well, there's the exception of 2001!! Is the Monolith a character, a machine, a device? The astute thing is not to have answered the question and never to have shown any ET if it had been a being.

Raoul