To be fair, loans aren't inherently unethical. Fractional reserve banking loans are unethical.

If you borrow money from your parents and they had to save that money by working hard then what you're really doing is taking their savings and spending it. Assuming you pay back the loan, you're not doing anything unethical because no new money has been created in that scenario. You spent the money and therefore your parents can't.

However, fractional reserve banking allows banks to loan money they don't have. In this case it's inflationary because you can spend money nobody earned.