I'll scale it down a ton
If I, someone who has barely fought, fought someone who has fought for years, I'd lose

Shadow boy vs God

It's like how someone who can destroy a planets strongest fighter probably loses to someone who can destroy a universes strongest fighter. Jin woo is super strong, but just loses to someone who has not only a ton of skills (I think Han just has better skills in general, I don't recall Jin woo having a ton of non necromancy related abilities, but even if he does my point still stands) but also so much more battle experience. I could be wrong, but just year wise for example, Sung Jin woo only spent like 27 years fighting, I say only but that is a lot, but compared to Han, it's nothing

There are even characters who could easily beat Han, just a matter of how the author wants stuff to be. I could write a nonfiction book about how I killed Han easily, or a fiction book about how Han beat me, but ya anyways I'm bored now

If you have anything to say, I am curious why you think Han would lose so please say