Simplifying and seeing it from a classical point of view (Cosmic and Atomic model of ferman), the magnetism or Magnetic Force can be considered as the REACTION force to gravity.
When a field of gravity force coheres mass, and so, great quantity of energy in that place of the space is accumulated, this provokes a great pressure of energy in that place, and as contrary and reaction force a new field (magnetism) force is born around this mass accumulation that treats of redistributing energy (mass or particles) in its field of action.

Foundations of the N-S Magnetic polarity

When any material body (either a star, planet; atomic nucleus, electron, etc.) rotates on itself, this makes also rotate (and to be deformed in spiral) to the gravitational and magnetic fields that surround this material body.
For this reason, if we bring near two bodies with spin and deformation of their fields of force, these fields will repel themselves if they are not aligned in the same turn sense, and they will be attracted and added if they are aligned in the same turn sense, say, N-S alignment.
This is exposed clearly in the following drawing.

As we can see, when the fields of magnetic and gravitational forces turn in the same sense, they can unite forming alone a common field.
Contrary, if they have contrary sense of turning, these fields of forces collide among them due to their contrary directions of motions.
So, this is the reason and foundations for needing to have the same sense of turn when two spinning body are closed among them.

Coils and magnets

Either coils or magnets have similar structure and functionality than the anterior case of spinning bodies, as for instance, atoms.
If we look to the following drawing, we can see as in the coils the electrons rotate or turn in one sense or in the contrary one, like the field of forces and electron take in any atoms.
So atoms and coils are similar in the creation of magnetic polarity around them. This case, two coils can attract between them if they are approximated in the N-S position, say, in the same sense of turning. And these coils will reject between them if they are approximated in the contrary sense of rotation.

Now well, if inside a coil we introduce a nucleus of iron, the coil positions to the atoms of iron are in the N-S direction, and this way, the polarity of the coil is summed to the polarity of the atoms of iron, given us much more potentiality of N-S polarity.
So, we can produce a magnet when we align the atoms of any iron material by mean of a electric coil, being permanent the magnet if the material is steel-iron due to this way the atoms will last orientated permanently.

Then, we can say:
The N-S polarity is alone the adequate alignment of the fields of forces of the spinning bodies, but not a particularity o duality of character of the magnetic fields.

This way, the magnetic polarity N-S is not an electric property but a mechanical resultant of sum and overlapping of fields of force.

In the following drawing we can see as the rotary magnetic fields are summed if they rotate in the same sense or subtracted if they rotate in the contrary sense.

The orbital cuts are the distances of magnetic balance on which (on the equator plane) the orbits of electrons are located.
The orbital cuts surround atoms (according to drawing) and the total sum of the orbital cuts of the magnet's atoms is what gives us the magnetic lines that surround this magnet, as we see, in the same structure than in its atoms.

The orientation of fields of force or magnetic polarity N-S is essential in the Cosmos for the construction of all the elements, substances and organism in the same one.
For the joining of atoms, formation of covalent bonds, of molecules, crystals, and all type of materials is necessary that the fields of force that surround atoms are aligned in the appropriate direction N-S and this way they can unite to form fields of forces common for all them.
In the future perhaps we see as elements, molecules and materials are studied from the point of view of the common field that they form and of the orbital ones (orbits with electrons) that maintain united the different atomic elements inside these materials.
In fact, for the formation of common orbital ones in molecules of any material it is necessary that atoms join in the appropriate direction N-S, and besides in bonds, at the appropriate distances so that the orbital ones have equivalent distances in the different atoms.
In this sense I put next the main molecular structures or types of bonds that can be gotten with this alignment N-S.