Background is designed to add a role-playing element to your character customization. You can treat it as such, or treat it as a way to customize your character.

Maybe you want to be consistent with the idea of a “cleric” and put Acolyte on it. Works, but boring, and won’t really add anything you don’t already have.

Maybe you want to treat it as a utility and throw “urchin” on your background. Suddenly you have rudimentary thief skills, how handy is that!

Basically, background is handy, but primarily for role-playing. You might want to invent your backstory first, and then pick the “background” that matches it.