Final answer:
Thomas Hobbes was the philosopher who first thought that the human person is completely individualistic in nature and only pursues their own self-interests.
Step-by-step explanation:
The philosopher who first thought that the human person is completely individualistic in nature, pursuing only their own self-interests, was Thomas Hobbes. In his famous book, Leviathan, Hobbes concluded that humans are naturally self-centered and quarrelsome, making them incapable of ruling themselves and in need of a strong leader to maintain order.