Life itself is a negation of all doubt, for life is and doubt negates all existence. Your queries regarding selfishness have been adequately answered, and your point concerning the one who imagines he has no self as he borrows from others should have also been answered. Borrowing is not effacement of ego but a strengthening of it, which is not difficult to understand. A shameless man is not an egoless man. We always distinguish between Sattva and Tamas .
Reality is One and undivided, though it is envisaged in variegated forms.