الإنسان له شعر، وكل شعر نبت
A human has hair, and every hair is something that grows.
The purported conclusion is الإنسان نبت
Therefore the human is a plant.
Having hair is not the same as being hair. The first premise concerns a part or possession of a human; the second concerns hair itself. The growth predicate belongs to hair, not automatically to the whole person.
At most one may conclude that a human possesses something that grows. A property of a part is not automatically a property of the whole.