Why are people Scots, Italian, French, Spanish? This shows their derivation, region, religion too, tradition, professions, etc. Caste also is similar. There are Maithil Brahmins, shows their origin from a particular part of India, shows that they may not be averse to non-veg. food which brahmins will not generally partake, their language will be Bhojpuri. Similarly, Jats. They are from Punjab, Haryana, Rajasthan and Western Uttar Pradesh. They are generally agriculturists. What I mean is that caste may not be a bad thing unless discrimination is practiced. People care about how they are identified. We have made discrimination illegal (five years in jail). Caste can continue. Actually, now it is a way to identify people to whom 'Affirmative action' is provided.
India had many migrants, invaders, has many tribes. Each wanted to keep their identity and traditions intact. India and Hinduism allowed them to do so. We did not make then melt into each other. We are like a stained glass window. The colors do not loose their identity but together make it varied and beautiful. Take for example, how many kinds of Jews we have in India. Each group came to India in a different period and from a different country: Cochin Jews, Madras Jews, Nagercoil Jews, Goan Jews, Baghdadi Jews, Bnei Manashe, Bene Israel, Bene Ephraim and Polish Jews.
History of the Jews in India - Wikipedia
en.wikipedia.org
Yes - but folks from some castes are considered less than human "Untouchables" --- this is not light, but darkness - and has little to do with folks being "Scots, Italian or French"
You failed to address your claim "Hindoo's never block the Light" -- Here we have an example - The Caste System - of major light blockage by Hindoo's.