One reads about loaning money in the past and the subtext is, if you were not repaid according to the terms of a note you held, you could get the debtor arrested. Eventually, debtors' prisons and being arrested for debt were largely eliminated in the USA and so those loaning money had more difficulty collecting. So did this cause the advent of loan sharks, people who could force the collection of money without resort to law -- essentially, before the government acted as the enforcers of debt and now loan sharks had to do it themselves?
No. Loan sharks arose out of the developments of the finance sector and The West.
Debtors prisons were eliminated prior to the Civil War, via the development of early bankruptcy laws.
The Civil War triggered an expansion in the financial economy. It, and the resulting recessions and banking crises led to westward expansion of financial services. The lack of regulatory oversight and large demand for financial services encouraged many actors, such as businessmen, merchants, even clergymen, to offer high-interest loans. By the late 19th century loan sharking was an established cottage industry, the term "loan shark" also entered the popular vernacular, replacing the previous term usury.
See: Loan Sharks: The Birth of Predatory Lending By Charles R. Geisst