At the time when he rescued hildegarde, he did say he accidentally brew an immortal potion and gave to to her to drink when they were young, so he could have been making and drinking the same potion but his common sense is like "it's just a immortal potion that anyone can make" and didn't...
Why did he not kill him? I hate mc that give excuses and then when the enemy came back stronger and do a genocide, he regretted not killing him earlier.
more like they want to repay Reiji for correcting the mistake that the king did. The gold coin is for his expenses if he ever runs away from the country (as quoted in his earlier statement of him "I didn't think you are stupid enough to show up") and the El statment of countless ways to weasel...
Not really, it is in literal sense. His body is hyuman that is half-adapted to Earth's conditions. Those that adapted to Earth is human whereas those that is not are hyuman (inferior human). That's why Root says he is a human but also not a human.
That was the guild before they fired mc, and now their combat power is down they don't want to pick a fight or else other guilds would finds out they become worthless and they will start attacking back.
From the past few chapters, I can say that the mc is over reliance on his skill. That's why...
I think you mixed up with another manga called skill lender. They fell back to noob level because the high level skill they want to use cannot activate due to them not having met the requirement, like not enough MP or VIT not high enough because of the rollback.