Teacher has done nothing all semester - should I say something? My Teacher for a required course has been completely unreliable for any amount of actual teaching. He is honestly the worst teacher myself or pretty much any of the other students have ever had. 

It's online, and it's actually very obvious that he's taken the format of his lesson plan directly from another teacher as many of his materials have their name listed instead of his. He'll ask for things on assignments that are very confusing (for instance, meet with your groups and discuss x) and the student body will be frantically messaging each other trying to figure out if we missed something because we were never assigned groups etc. It's not just us asking each other either, we send him messages. At several points it took him until after the assignment's deadline to respond to any one of us, so this isn't a one off occurrence. 

His version of MLA format that he expects is adjusted, but how it's adjusted is up to speculation and seems almost dependent on how he's feeling. The only thing that he actually has to grade (since everything is online - he just pointed us to do pre-programmed worksheets from the book company) are three written reports at the tail end of the semester. 

The problem with those reports is that because of the unclear formatting I, and a few others, received a drop in grade with no explanation or "this isn't what I was looking for". Nevermind that we've been wondering what he's been looking for but rarely responds to anyone about anything. The same thing happened with the next assignment but I lost significantly fewer points and I have zero idea what the difference was between the two formats. 

I understand that Teachers have to work incredibly hard and they are often undervalued comparatively to that, but even giving him an incredible amount of leeway I have to be honest and say that he should never have picked up this course if he wasn't actually going to teach us. Is this something that I should bring up to the school's HR? This semester has been absolute torture for all of us and it's ridiculous that anyone should be "taught" like this.
Not if this is the format you're going to bring your complaint in. You really need to get a group together with very clear, well documented, explicit examples of the problem behavior and bring that to the attention of the administration. You've probably got an ombudsman who would be a good first place to bring such a complaint to.