The synopsis is not wrong, this really is a story of a daily everyman. It's a strange incongruence because I know when most people read, they put themselves in the main character's shoes, they revel in the strength and ability that they will never experience in real life.
In this story, the MC is not talented, he is cowardly as f**k, and because of that fear, he hurts people around him, typical of a delinquent. Later on, as actual danger approaches, actual danger that his yankee bluster can't deal with comes along, he just sits there frozen in fear, or spends most of his time thinking emo, angsty thoughts. A normal farmer's kid, surrounded and best friends with someone this world's most powerful people who believe in him to the death, but he will keep repeating that he's not worth it, sort of like Harry Potter, but with even less self esteem. Again, typical of most delinquents. They will keep trying to push him to be a better man, but you'll have to read about him being completely uninterested in developing his potential and throwing everything away for what most would consider a very tiny and stupid goal despite so many good things around him.
And that's not even taking into account the REALLY stupid stuff he does while acting arrogant and super self confident. Again, like a typical yankee. The only reason he's still alive, is because of plot armor. Because how else would a super strong delusional yandere hell bent on massacring the demon race suddenly transform into a super strong delusional yandere hell bent on raping your 10 year old ass, just long enough for someone who is actually strong enough to arrive?
Then it abruptly takes a jarring turn into a more cheerful mood and suddenly no one is sad that their father died anymore. It's marginally better after the time skip, but again, it's VERY draggy and a pain in the ass to read, and because there's more action, there's also more chances for MC to do REALLY STUPID THINGS again.
For example, his personality regresses because he again becomes very aggressive and uncaring to everything in this world, so its VERY frustrating to read about how callous he can be despite having it so good. E.g. He has people around him that trust him with their lives, but on his journey he still refuses to tell them whats going on despite not even bothering to hide that he's different from them. This attitude eventually became so annoying that I couldn't keep reading.
In summary, the story is bad enough that the MC is powerless as sh*t in the grand scheme of things, but his useless bluster when interacting with the world, zero social skills despite having a healthy social life in this world since he was five years old and refusal to grow into a better person despite repeatedly making promises to do exactly that again and again each time something happens was cringy enough that I could not read past chapter 50. I'm sorry, but this is where I bow out.