What are we?

Animals.

Human beings are not angels fallen from the sky, nor cries in the night, nor pure indeterminacy; nor are we machines or computers. What we are is animals. We give birth, are born, eat, breathe, and die like animals. And most of our genes are devoted to encoding our animal functions. If you want to know what an animal is like, look in the mirror. Any conception of the human being that tries to distance us from our natural reality is a vain exercise in ignorance, self-deception, and superstition. If we want to truly know ourselves and understand what we really are—if we value self-awareness and truth—we must begin by accepting ourselves as living beings and as animals.
— Jesús Mosterín, The Kingdom of Animals (2013)

But being animals sounds degrading to our human ego. So, to soften the blow, we pair it with ‘rational animals’ — but the conflict is already there.

Man finds himself in the uncomfortable and embarrassing situation of being an animal who is also a spiritual being conscious of himself. Man is aware that the spiritual aspect of his nature grants him a dignity that other animals do not possess, and feels that he should maintain that dignity. That is why human beings are ashamed of the organs, functions, and appetites they share with nonhuman animals, which undermine human dignity because they remind us of our physiological kinship with beasts. Nonhuman animals are not embarrassed by the functioning of their physical nature because they have no self-awareness. The anxiety caused by the fear of losing dignity and the humiliation of actually losing it are specifically human miseries.

Humanity’s device for maintaining dignity despite the animal aspects of man’s nature is to distinguish ourselves from nonhuman animals by inventing certain conventions (which animals cannot emulate) to deal with those animal functions and organs that are part of our constitution and unavoidable biological heritage. A test of culture or civilization is the degree to which we manage, through artificial conventions, to differentiate the way we address those physical organs and functions common to all animals.
— Arnold J. Toynbee and Daisaku Ikeda, Choose Life (1984)