Some speculation on Jax lore
I'm pulling ideas out of my ass rn but here are some core ideas that I believe Jax's direction should be taken. This is also disregarding his current bio as I think it isn't a very satisfying progression for his character and feels very odd (In my opinion)
After the fall of Icathia, Jax had to blend in best he could. He traveled Shurima for decades, not letting on he was Icathian. I'm sure he would be subject to a lot of discrimination. And at the time I am willing to guess it wasn't particularly unusual for non-human kind to be around, but as time went on and Shurima descended into collapse, he moved on to Valoran, Blessed Isles, Ionia, Freljord, Ixaocan, Targon, Freljord. Pretty much a nomad soul searching after he lost his people and culture. As time went on he had to withdraw more and more because he wasn't human and people were finding him scary. I would guess he chilled in Ixaocan for a long time or another very secluded place. Possibly even other continents? (It could make sense. Jax has been away from the known continents and decides to come back after hearing about the return of Azir or something). The thing is, I don't see how Jax would have done anything particularly active against the void because he wouldn't have any knowledge about what he could do.
So he comes back to the known world, I would love to explore his "recruitment" of people. Some champions that are probable candidates in my opinion are:


I could see him finding Zilean's tower in the wastelands of Icathia. The void activity probably has gone down a lot in the centuries. Maybe he could meet Zilean and that would spark his drive to revive Icathia with Zilean's help.
They do fight in his color story and someone of her talent is somebody he would want to join his cause.