And of course you will be able to kill a sheep, but you better should not confront the troll back in the woods yet. You will die often, so you think it is difficult, but actually you just have to learn about your own abilities.
I remember that many years ago when I played Gothic 2 the first time, my char was really weak because I didnt really understand all the skilling stuff (my weapon abilities were always 10% because I couldnt see any benefit in putting points there - a big mistake). So that my char was almost as weak as in the beginning at the game, but I still did it to chapter 3 or 4 with him, even if it took some time to do so.
Also I found out many tricks how to kill most monsters, sometimes even without loosing energy. Now I am even able to kill the black troll in close combat right from start, with the wooden weapon you will find at the very beginning at level 1. It is really funny that you can even kill the second strongest monster (just dragons are stronger) so easily if you know how to do it...
My tactic is: run to the troll and try to be fast enough to get behind him, now get your weapon in your hands and hit him from behind one or two times, while he tries to rotate, walk around him so that you are again behind him, 1 or 2 hits, walk again behind him, 1 or 2 hits, walk again behind him and so on until he dies.
He gives a good EXP boost at the beginning, as I remember you will even climb 2 or 3 levels up just by killing him at the very beginning.
What I want to say is that while you get easily killed when you go to a place that is to strong for you yet, you in the other hand will be also able to survive, when you know how to do so.
But one of the biggest difficulties in this game compared to others may be that everything is limited. You just cant level up with unlimited amount of weak monsters and then go to a strong place. Also you have to think twice where to put a skillpoint and when to put it there. You also have to manage all your potions. If you dont do so, you will went in to big trouble later in the game. I think this is one of the biggest difficulties in Gothic 2, especially if you play it the first time.