Why is Jax a champion?

Who cares about Riven? The most broken champ has always been Jax. With few disadvantages and a ton of damage that only takes auto attacking, it's not fun at all to have him in a game. Riven at least has to choose when and where to use her skills. And has a real backstory. The story for Jax is just "He's really strong for some mysterious reason and we let him in." No explanation. Just a random assortment of physical traits and a cocky attitude. Seriously, it's like a junior high D&D character who's only trait is "wins at everything". That is way more annoying than a daring swordswoman who has some risk to her engage.

Let's up the bar. Even if he doesn't get a rework, at least give him a real story so i can imagine WHY I'm getting smashed by some idiot with no skill.