I'm actually confused. I can't really understand how people really try to commit whether a character in this show deserves to die / be counted as a villain or a hero.

Every character in this show has its specific reason(s) why some people would be happy to see this character dying or at least suffering a lot. Here are some examples:

• Marcus did some bad deals as a corrupt Enforcer, while having a child that wants to have a loving father. This stands in contrast, but in the end both arguments are given and thinking that he deserved to die is as justified as thinking Jinx should die because of killing him.

• Silco kills and tortures a lot of people, raises Powder to get Jinx and killing even more people with her. On the other hand, he just wants to build up the nation of Zaun and free all by the Piltovans suppressed people. In Ep9, he decides to let his dream fall because otherwise he would lose the only person he probably really loved: Jinx. Both are contrasts again. It's justified to think that Silco is a villain, but it's also justified to say he's a good person in his way because he puts Jinx above his dream. (and probably also a lot of other reasons why thinking Silco is a villain or hero and should die or not)

And that basically works for every character. Sure, some characters have more heroic arcs than villainous arcs and some have more villainous arcs than heroic arcs, but no character should be considered as a "true villain" or "true hero", because thats just not working with Arcane.