An emotion I associate with creatureness is persistance. Whether it's a human trying hard to study for an exam or an animal trying to get food, I think creatures have a tendency to figure out creative solutions to get what they want.
When thinking of an artifical creature that expresses this act, I thought of the art installation called Round Table by Chloe U-Ram, where 18 strawmen prevent a ball from falling off the platform. But once I looked into the art installation for this assignment, I found out that I'd misunderstood the artist's interpretation; the strawmen are headless, and they each stand up to try to claim the straw head (the ball) as their own. And as a result, the table tilts away from the strawman, rolling the head away, and it fails to claim it. I decided to stick with this art installation for the assignment, and instead pivoted my creature trait to competitiveness.
I think a simple creature that could reflect competitiveness might be an object with two parts that have to work together to succeed, but they refuse to do so. For example, a pair of scissors trying to cut paper, but the two sides aren't working in sync and never manage to cut the paper.