Objective morality as a proper basic belief

[Fidel_Castronaut]

I think you're conflating and equivocating topics to mash out a seeming contradiction.

Subjectivity does not preclude objective results, nether does it preclude someone saying 'that's wrong', and neither does it preclude a society basing legislative and judicial precedents and structural frameworks upon it. . Some people may believe rape is ok, but you'd be hard pushed to find many that would agree with that. In wars the women are often the prize and people turn a blind eye to it, or worse, actively encourage it (example above from downbeatplumb). Does that not directly evidence the subjective nature of it?

Morality is a human construct and has been established over the course of both our biological and societal evolution. Precedent, consensus, and the interactions of agential and structural discourses about what value we place on both society and its laws/rules. That's the cornerstone of a discussion on morality and ethics, and as such I think that would be a good place to start.