Why does believing society had an incorrect view of rights in the past entail such a thing? It's compatible both with believing that society today has a correct view of rights and the opposite, believing that society today has an incorrect view of rights - even if that view is different than before.
Having an opinion doesn't make that opinion an objective fact!
Having an opinion doesn't make that opinion fact. But if you say that one opinion is in any way superior to another opinion then you are recognizing that there is something to measure those opinions against. There is some truth that we are trying to discover through reason.
Having an opinion doesn't make that opinion an objective fact!