I'm only a novice like you but a few years up the road. All I can say is just accept what you've been told about this and eventually you'll get used to it. You are trying to absorb a lot of things at once and not just about relativity itself but the terminology and the way scientists think. Eventually, it will slowly come together. When you see someone like Mordred writing the way he does, that's more than twenty years of thinking about science and methodically unpicking what it means. You won't get your head around relativity in a few posts.