It may have been 100,000 years for the protaganist, but it's only been like what, a couple hours at most for everyone else? The weakest person you know suddenly summons a literal god? Arnold is somehow able to guess that Kai is at the abillity of someone that trained for a millenia? Kai kills two people in the previous chapter (and it seems to be on complete accident since he mentions "does this break so easily" in the previous chapter). Would be more interesting if he at least just blows off the sword emperor's arm by accident.
Story would be much more interesting if the author had the guts to make him go batshit crazy. Some woman who you knew for less than 0.0001% of your life "appoints" you to serve under her? It would make more sense if he just instantly killed her. After all, he basically spent his entire life nearly killing everyone he met in the dungeon, it would make more sense if any idea of the world he has is completely fucked up at this point. His companions are a dragon loli and monsers/gods he enslaved, which he controlled by strength. Basically every being he meets for 100,000 years he eats, enslaves, and/or fights. Story would be more interesting if it went the route of him basically becoming a villain/god of this world or a story where he realizes how fucked up he is and tries to regain his humanity before it's too late but that's probably not going to happen.
Also, so many authors always take democracy as a given natural good. There's a reason throughout history most countries and nations weren't democratic. It took hundreds of years of philosophy, revolutions, economic progress etc. for democracy to be able to actually become a dominant form of government. Considering Kai literally spent 100,000 years alone if he even bothered to think about human forms of government it's unlikely he would come up with democracy as something he'd want to implement, especially considering those subordinates of his that happen to be gods are basically his slave summons.