The human right to life is the primary inalienable right, and that right is what Ayn Rand works up to in the passages I cited. She uses reason to show that Man's right to life is a natural right, and then bases her rational ethical system on that one right.
In your dictionary quotations for selfishness, I detect the connotation of evil in each of your three definitions. That connotation is probably a result of the popularity given the philosophically socialist ethical system of altruism.
I just noticed that my "1936" dictionary was copyrighted in 1936 and printed in 1946, and it defines selfish as ...
selfish ... Caring unduly or supremely for oneself regarding one's own comfort, advantage, etc., in disregard, or at the expense of, that of others. -- selfishness, n.
And yes, that does differ from the unevil definition that Ayn Rand gives for selfishness, but -- for sure -- a natural concern for one's own self interest is not evil.
So now I wonder what eighteenth and nineteenth century dictionaries would say ... In those eras when America was founded and before the socialist ethics of altruism swept round the world.