Cream rises to the top. That implies it is "better than" that which lies below. On the evolutionary scale humans are at the top, right? Why?

I think there are many animals who are "better than" humans. Kinder. More loyal. Honest. Etcetera etcetera etcetera. Which animal would you place at the top because of its nature, the way it lives its life and how it relates to other members of its species?