Korvac has a long history, most of which doesn't even take place in our universe, so who really cares? I say "our universe" as if anything in Marvel is really in our universe, but you know what I mean. He's taken many different forms over the years, kind of like Seth Rogen. He was super powerful, but he felt like no one appreciated his power. He started being annoying, trying to impress everyone, but that got him into some trouble where a powerful being ripped him in half. You know, standard stuff that happens when you're being a bitch.
This dude hacked into Galactus to become more as powerful as a god, which is when he took his human-like form. Who hacks into Galactus though? I wonder if he stole any bitcoin from him. You know Galactus is rolling in bitcoin.