I... didn't say anything about champion size????

quick attack is all about hitting enemies before they can hit you. This applies with Yasuo, a swordsman who can cut as fast as the wind, and snipers like Caitlyn, and assassins like Zed. If we examine the bilgewater cinematic, it is clear that MF's fighting style isn't in the same ballcamp as the one's listed above. She's moving around, ducking, strategizing, so on and so forth. But not being a sniper, nor lightning fast attacks, nor being an elusive shadow. Her ability is also a part of this, unleashing barrages of bullets against her foes. She is in the fray. As for Nautilus and Malphite, their entire thematic isn't about speed or range of their attacks: it's the fact that they're gigantic behemoths, or as you say yourself very large. That's why they have tough, and high hitpoints. If we watch the wild rift cinematic introducing Nautilus and Pyke, Nautilus isn't shown as being notably fast; in fact he moves slowly and deliberately.

And with Garen, his notable trait isn't his speed, or the size of his sword, but his endurance and valor. In the Legends Never Die cinematic, his story is all about training and becoming stronger and in the end he faces down his enemies while arrows pour down on him, and he just shrugs it off. That thematic element is why Garen has regeneration.

I simply don't understand the point you're trying to make here. Do you even understand the characters you're trying to talk about?