As I have been learning from The Sacred Tree: Reflections on Native American Spirituality which these figures are from, the Medicine Wheel symbol is used by many native people in North and South America to represent many different things that are sets of four.
The circle is used to both illustrate that the things represented (race, elements, etc) are connected to each other as part of a continuum. And that they are equal to, and must be in balance with each other.
All people, of all races, are each other’s relations and equal.
All of the elements of our environment are critical and must be respected and protected. It is fascinating, that hundreds of years ago native people knew that if we poison our air, as we have with carbon dioxide, that would also hurt the water, for example, as the carbon dioxide absorbed from the air is converted to carbonic acid in the water.
Likewise the importance of the connections and balance of these aspects of human nature. In our society today the spiritual part seems to be especially diminished.
So many of the problems we face today relate to upsetting these balances and relationships.
The solutions are restoring the balances.