Would you still call it a "thing" after you discovered the spaceship?

Maybe come up with a new name for the species? They have scientists in their group.

Cuz The Thing sounds cooler than alien lifeform.

It's probably like how no one in The Walking Dead has ever heard the word "zombie". I've always found it silly, personally. I don't understand the need to separate your work from the rest of the history of pop culture. It's always seemed like a desperate attempt to be unique and original, to me.

I'd call it Pipsy and give it little treats.

judging it based on human morality. It has ruthlessly killed several of your friends so you don't want to humanize it. Therefore you just call it a thing.

I think Carpenter explained why they never called the thing an "alien", even though it clearly is one. What he said was these are all blue-collar working-class men who would have a hard time accepting silly science-fictiony elements like aliens to exist. These are guys who aren't easily amused by fairy tales and scary stories, and thus wouldn't immediately admit their belief in aliens. Instead, it's just "some thing" to them.