Common

You come from the ranks of those people who are average in everything. Your Common. What made you leave your average life to become someone who is not average at all? Did your village get attacked by orcs, leading you to become a ranger or paladin? Did you go to a temple to make the normal praying rituals, and was blessed by a god, leading you to become a cleric? Did you find a magical scroll hidden back on a shelf in a library, which lead you to become a wizard or warlock?

What ever the reason, this background can work for any class, any character at all.

Tool Proficiencies: Even though you were an average person, you had to learn a trade of some kind. You get to pick a tool of your choice.

Languages: You have to be able to communicate, so you learned one common language and common.

Equipment: Some money and the tools you trained with are really all you need.