Next episode.

Don't really follow the story. Ok, MC are super-powerful and want to ensure human domination of other races.

What's good in it for others groups? They shown no better or worse than humans, they want pretty much the same thing (their own domination at expense of others). Why we should root for the yet-another-imba-cheater MC and not the others?

I believe you have to start from the beginning, first his brother died because of it. Then he was chased down just because he show talent that why he used the tiger king incarnation. All in all, it's my clan against yours, the humans talents were being assassinated left and right. Of course, there are traitors but the main reason MC gets so strong it's the same reason you're questioning this whole show.

I watched it for some episodes and got that part - MC are chased because he are powerful (but it means he are threat to opponent groups), but he is doing the same thing - he kills opponents from other groups without much moral issues focusing on strong ones so he doing the same thing. Why root for him and not other groups, which are not better but not worser.

I also tried googling for source novel and googletranslating some parts of it, and as far as I understood from few final chapters, his victory ended up in other races genocide, where he used demon spirits for leveling up in final few dozen of chapters, after overrunning their island and slaughtering their military. So he is no better from moral point of view than his enemies, just more powerful due to impenetrable plot armor to win.

This show is not about morality but dominance and survival of their race. There is no hero in this story and MC has never claimed to be one, he has explicitly stated he wants to conquer the world.

Because he's the MC. Whether or not you root for someone is irrelevant to whether or not they are good.