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>Lending money at interest
No. A mutuum at interest. A contract for the loan of goods which will be used or consumed by the borrower, to be repaid with goods of an equivalent quantity and quality. That may be money, it may be grain, it does not matter. What matters is that the lent good is not intended to be returned but consumed.
>Does the person who lent you the money now own the business?
They own whatever they lent you. If you want a loan to buy a car, the licit option is the lender purchases the car, and loans it to you. You pay them for this service. If you cease payment, they reclaim their car. They have no further recourse, you can not become indebted with no ability to repay. That is the core reason usury was illicit, the debt trap.