If level 1s can beat level 5s in a fair fight then wouldnt that make the leveling system kind of pointless?
Same for level 5s beating level 13s.
It doesnt happen in any other games so I see no reason for it to happen in Graal.
Besides you can technically catch up.
The experience needed to change level doubles each time.
So while you only need 4, 8 and 16000 the person 5 levels ahead needs 128, 256 and 512000. Plus lower levels get more experience. So you could get eventually to the same level as another person if you both killed monsters an equal number of times.