Tell me something at what point did I ever say the only thing that WW will be able to do is split push. Obviously he's going to gank during the laning phase but once that's over and his ability to makes picks as easily is gone he's going to turn into a split pusher, much like Shaco but unlike Shaco due to to the nature of his kit plus the items (most likely buriser items) he's going to be incredibly powerful late game in a 1v1 situation because of how much free life steal he gets plus his damage reduction.
As for fitting his lore I can't say much since I don't remember his old lore but wasn't he like a hunter that tried to hunt down Soraka.
As for you last point it seems to me that you are the one that's not understanding me. As you said he has better survivability, damage output and mobility while also keeping his AD and HP.
Do you remember when Riot changed Darius's passive from magic to AD because it was unfair since it made building against him hard since his passive meant you won since the enemy laner had to rush armor but your passive still did a lot of damage , well its the same thing here. All of his ability has mixed damage in it. His passive adds 10 magic damage at level 1 while at 18 it adds 44, with a last wit that's 84 magic damage per AA but on top of that it heals you for the same amount below 50% health while below 25% it triples, meaning its 132 at level 18 but when you add Runic armor that makes his life steal 8% stronger, plus Spirit Visage which increases the effectiveness of all health restoration by 25% and with warlords blood lust his life steal is going to become stupidly strong
His Q again has mixed damage, It does % Hp magic damage while also having a 120 AD scaling on a 6 second cool down while also healing you from 30-70%
His W passively gives attack speed against champions below 50% health all the way up to 110% and with the bonus movement speed its going to be next to impossible to get away from him, plus his E gives him damage % reduction while also letting him cc multi-able enemy.
Then his ult and oh look that, again its mixed damage that's going to apply all on hit effects and heal him for 100% of all the damage he deals.
The problem that I have with this kit is that it has so much sustain in it that hes going to be nearly impossible to 1v1, making him a fantastic Split pusher