The caste system existed long before Europeans ruled India. Caste system has roots in the Vedic society.
"The varnas originated in Vedic society (c. 1500–500 BCE). The first three groups, Brahmins, Kshatriyas and Vaishya have parallels with other Indo-European societies, while the addition of the Shudras is probably a Brahmanical invention from northern India."
... "there is no evidence in the Rigveda for an elaborate, much-subdivided and overarching caste system" [1]
Caste and any discrimination is abhorrent, and like others have commented is a more recent phenomenon. In old times and today, anyone can become a priest/Brahmin by learning. [2]
The "Caste system" has European roots connected to the monopoly of one book, one god and the all powerful church.
In Europe the king was the representative of god and got his powers through the church. Then came the merchants, landowners who funded the state. Artisans took the next rung. The unskilled workers took the most menial jobs came last.
We call this today as the class system but this was the original caste system imported from Europe and applied on the native population of India.
While one can not deny that there were/are different communities and a kind of class hierarchies in India just like in the rest of the world. The rigid caste system is actually the work of the Church. In India each community had its own gods and its own chieftains and priests.
Somehow the poverty and destitution seems to be always blamed on the natives.
Moreover Caste system is a European system introduced by the British to divide up communities.