I have a theory on Caste System in India. I present the brief synopsis here. If you agree with the logic, then you would agree that there needs a recasting of the social structure as the modern realities have shifted very far away from the realities existing about 3000-5000 years ago.
At first, when man came together to live in a social formation, there were no caste. Everybody had to hunt, gather and cultivate. Large formation of social gathering came into existence only after human beings adopted Agriculture as a source of getting food. Man realised that collectively they could produce and secure more; rather than putting personal effort. So, now there was a need for specialisation.
So, the society selected the most physically strong people with reasonable amount of mental capacity and asked them to specialise in protection of the society. They were called the Kshatriyas or the Warriors.
Next, the society turned to the people who were not so physically strong. However, these people had good mental abilities. Man always needed connecting to the their Ancestors and it was a necessity for pleasing the Gods who were supposed to protect their fields and houses. So, society assigned this specific task to a group of people and they are called Brahmans.
There were still some people remaining in the society. These people were neither physically very strong nor were mentally very capable. So, they were assigned to do trade goods produced by Kshatriyas and Brahmans. These people were called Vaisyas or Traders.
Lastly, the people who did not fit all the above three categories, the people were assigned to help all others. These people were called Shudras.
Now, Man noticed that new-born carry the traits of the parents. Also, the traits of father and mother collectively form the traits of the new-born. So, to enhance the chance of stronger warriors, they asked Kshatriya boy to marry Kshatriya girl. The same logic was applied to others as well.
Now, Kshatriyas soon found that what the society needs the most is security from animals and invaders. So, they announced their superior job allocation to the society. In return, the society had to compensate them; which in later turned into what we refer to as tax.
The Kshatriyas needed part of the society as their confidant and they chose the Brahmans as they were mentally superior. In this way, superiority of castes came into existence.