Question

why the magnets are depicted as north and south poles??

Answer 1

This is an historical artifact from the days when the study of magnetism was limited to lodestones suspended from strings. Note that the "north pole" is defined as the "north-seeking" pole of the suspended magnet. Thus the earth's magnetic south pole is at the geographic north (so the north-seeking pole of the magnet is attracted by the earth's pole that is in northern Canada).