Commercial banks earn money in a variety of ways:
1. private loan interest
2. mortgage interest
3. account maintenance fees
4. transaction fees
5. loan origination fees
6. holding securities
7. proprietary trading
8. wealth mgmt and advisory services
9. credit card interest
10. forex trading
11. underwriting services
12. investment banking (mergers and acquisition advisory, capital raising, market making
13. Loan securitization
14. mutual fund fees
15. etf trading fees
16. insurance products
17. safe deposit boxes
18. federal funds lending
19. holding government treasuries which provide a yield.
Those are some off the top of my head.