Is it possible to hit challenger as a normal person

Where there is a will there is a way. But sadly no probably not, unless you're some sort of moba godchild. With it being season 8 and there are still a lot of vets playing the game I don't foresee a typical / casual player (2-5 games per day MAX) really solo climbing to challanger vs someone who spends a retarded amount of time (8+ hours) a day on league. But you might be able to do it if you're good enough.