If you find any error, either grammatical or lexical, feel free to say it in the comments. English is not my main language and i still make mistake. Anyway talking about this novel, yes it has a system ability, yes it would be weak to strong, no the MC will not be utterly stupid, no he will not save people but hide and not tell that it's him that save them, harem will probably won't happen or at least won't be "find good-looking woman next to strong opponent, beat opponent, woman fall magically in love with the MC".
This novel is supposed to be funny but still realistic so yes sometimes plot-armor-san will make his appartion but he will get kicked away very quickly.
About the MC, he will be more sneaky and cunning than ruthless and savage. I mean he already had that mentality in his human life he will keep it. Next, i will try to not make the whole world stupid, except the gods, nearly all of them will be beyond redemption.
About the world, it will be the basic fantasy world, you have the human race, elf, dwarf, lich, undead, lizardmen, beastmen (with different species). Magic will be more important than technologies except for dwarves, gobelins and ratmen.
Next the rate of chapter, i will probably post 1-2 chapter daily, if i don't do it you can spam the 1 star review.