Just clarifying that discrimination doesn't have to result in being fired or passed over for a promotion to count as discrimination.
1. If a bunch of co-workers who are vegetarian due to their ancestry choose to exclude me from lunches because I want to eat meat, can I sue them for caste discrimination?
2. If someone makes fun of me because I wear a mark on my forehead, can I sue them for caste discrimination?
All laws need to have bounds that operate within the constraints of the US Constitution. This is why I was limiting the scope of my comments to hiring/firing/promotion related topics. I am sympathetic to social issues like what OP is talking about, but also do not believe that new laws can solve all of them.
Also, the existence of such a law should have a chilling effect on this behaviour. Even if it doesn't get rid of it. E.g. presumably HR policies & training will have to be updated to highlight it on pain of exposing employers to legal action.