So, Rittenhouse did nothing wrong legally and Arbery's killers committed obvious murder. Rittenhouse shot his pursuers in self defense (in the moment) while Arbery did not threaten his murderers. That seems pretty different to me.
And yes, I do think our gun laws and people's attitudes about them suck. I am horrified that we allow vigilantism and that people are celebrated for it. That sounds like something that would happen in a third world country.