I can only say that I'm a total sucker to reincarnation stories, especially those where protagonist becomes non-human. So I present one of my favorites - Goblin kingdom. As name suggests, its about a man who's born as a goblin and strives to create a kingdom with them. It's somewhat of a mix of series "Kingdom" and "Re: Monster". There's one key point though, the protagonist is NOT absurdly overpowered, his origins certainly gives him an edge in standing above everyone else, but he earns his spot with his sweat and blood. A rather serious and awesome story. Hope you'll like it.
And as always, support original author and translator.