Did Darwin borrow from Adam Smith, and does evolution justify usury or capitalism?

No. Darwin did not borrow his biological ideas from Adam Smith. He was influenced by earlier naturalists and geologists who speculated on gradual change. The claim that Darwin’s “survival of the fittest” arose from economic theory is exaggerated. As for usury, the Church distinguishes between legitimate interest and exploitative lending. The moral law condemns demanding payment for time itself, but it allows compensation for loss or risk. Compound interest that crushes the borrower is sinful. Just recompense for delay or default is not. The principle behind the medieval prohibitions was charity, not hostility to commerce. Modern economics must still be governed by justice and mercy. The logic of evolution and the logic of finance have nothing in common; both can be used or abused according to moral law.