Arilyn
Hero
And it would be great, if the rules actually said that. Instead, the rules say that you can take any background, swap out the proficiencies and feature however you feel like (keeping the description/flavor/fluff of the lore intact), and any DM is a jerk if they ask you to justify it.
What the background rules should have said: "Figure out your background. That is what you did before you were an adventurer. Other characters may react to you based on this. Choose two skill proficiencies and two languages or tool proficiencies that reflect your background. Here are some examples."
What the background rules actually say: "Here are some some codified backgrounds. Each background gives you two skill proficiencies, two languages and/or tool proficiencies, and a feature which determines how other characters react to you. Feel free to mix and match them arbitrarily."
Okay, while you are technically right, I think the spirit of the rules is meant to allow players to create their own backgrounds. Any half way competent GM is not going to allow a jumble of proficiencies without an explanation or unifying theme. There are far too many campaign worlds and player ideas to restrict backgrounds to an official set list.