Y did Renekton get a buff???

Because the only way he can do that is if he took Ignite and he's facing a very bad top laner who let him do his level 2 cheese free, twice. Anything else and he has a high likelihood of dying to the turret due to his W's cast time and needing E to escape. This would not be a problem except a decent top laner will just stand back enough that he has to use E twice to even reach them, which leaves him no escape and likely dead.

For why he's strong early? Because unless fed he's useless mid game, and he falls off like a brick past that. He's reasonably easy to kite, only has 1 way to engage, and does nothing unless in melee range. He relies entirely on brutal early game presence because past the early game he's absolute shit.

His entire purpose is for his early game dominance, seeing as how he falls off late game

So while your exaggeration makes him seem op, it's really quite balanced seeing how clear cut his weaknesses are

You could try not fighting him at level 1, losing the fight, and then putting yourself in a position to get dove at at level 2? It works pretty well for me when I play against him.

I hope you realise that renektons buff was to his ultimate. So keep complaining when you dont know what you're talking about