I have never strongly associated the word master with slavery. I think of a master copy or a ships master, master/apprentice as much as anything. Master/slave specifically seems problematic. It does express the relationship between the software components better than most alternatives but I am happy to defer to people who know more than me on the social costs of keeping that terminology.

There was indentured labour (effectively slavery though it was technically outlawed) practised in my country but many people aren't even aware of it and it hasn't created huge racial divides, civil war and political division that persists to today. I don't feel qualified to have an opinion either way. I find 'main' totally acceptable for the default git branch.

I think change should be real and pragmatic and improve peoples lives, not just symbolic change to appease peoples guilt, but the truth is symbolic changes can have an impact. I am totally fine with saying sorry to my countries indigenous people. It isn't an admission I have personally done anything horrible myself to them. It is just saying sorry. It is what a decent person would do when they saw an injustice done. But I guess seeing that takes a certain level of emotional maturity and I guess that is often missing from these debates.