Third party v. first party claims
Your business is a "first party." When someone files a claim against you, they are a "third party." Liability coverage protects your business from paying large amounts of money out of pocket. In the event a claim is successful, you would be responsible for shoveling over thousands, if not hundreds of thousands, of dollars.
These claims are covered under general liability. Claims from within your business or do "to your business" (like theft) are claims from the first party to the third party and are not covered. General liability is specifically a defense from third-party claims.
By having coverage, you're able to protect yourself from third-party claims against you. Plans and certificates of insurance can change based on coverage.