Just as the sun replaces the earth as the center of our cosmos in Copernicus’ cosmological system, so humanity itself replaces God at the center of humanity’s consciousness in the Enlightenment.
This is what Beauvoir means when she "rejects humanity"
Beauvoir rejects these systems of absolutes in favor of ethical projects that acknowledge our limits and recognize the future as open.
This is exquisitely humble for a godless.
Describing consciousness as ambiguous, Beauvoir identifies our ambiguity with the idea of failure. We can never fulfill our passion for meaning in either of its intentional expressions; that is, we will never succeed in fully revealing the meaning of the world, and never become God, the author of the meaning of the world.
We are imperfect at meaning-making. From the standpoint of an individual consciousness, then, the god-concerning project of absolute meaning can never be completed.
The Ethics of Ambiguity opens with an account of intentionality which designates the meaning-disclosing, meaning-making and meaning-desiring activities of consciousness as both insistent and ambiguous—insistent in that they are spontaneous and unstoppable; ambiguous in that they preclude any possibility of self-unification or closure.
We discover, make, and desire meaning. This is at the foundation of being conscious.
Thoughts/representations of the world around us, ("intentionalities") that bubble up in our consciousness... we continually have them wether or not we like it. And by simply having a subjective experience of the world, Beauvoir says, we are bound to meaning-seeking/disclosing/creating activity.
She identifies herself as an existentialist and identifies existentialism as the philosophy of our (her) times because it is the only philosophy that takes the question of evil seriously. It is the only philosophy prepared to counter Dostoevsky’s claim that without God everything is permissible.
Dostoevsky's ethics rely on a top-down God upon which each of us depend.
Beauvoir's existentialism makes us interdependent on each other.
“A man alone in the world would be paralyzed by … the vanity of all of his goals. But man is not alone in the world” (Pyrrhus and Cinéas, 42).