Past how people look the first things we learn about them is what they are good at.
People are passionate about what they are good at.
Let me just make something clear your MC needs skills otherwise he won’t survive it through the book but that doesn’t mean he has to be good at everything.
He just needs to be good at one thing sometimes. A nice piece of advice I read one said give your MC a skill and make sure he knows it well. Your MC doesn’t know a few languages moderately well he speaks eight different languages fluently.
I don’t think his skill set should be just random because everything comes from somewhere.
Your MC can’t just sing. He sings because his mother sang to him every night as a kid.
Can your main character through a knife that it hits the bulls-eye ten out of ten times? It is because she was raised by a criminal and constantly fought to prove herself.
I don’t think I can properly tell you where to find your MC skills but I suggest you go write down what he does in his day to day life and figure out for yourself what your hero can do.