> To me it has to do with aligning your goals with the goals of others.

That is fine but you have already put it relative to what you think. If everybody does that, then morality will differ from a person to another; and thus it becomes meaningless.

You can do that with any word. I mean, I might define "up and down" differently than you. You might think they have to do with gravity, the orientation of the head and eyes, or the center of the earth. But most of the time, we agree on what they mean because we aren't in outer space or hanging upside down while using them in conversation. We can adapt to situations like a piece of paper on a horizontal table, where "up" has more to do with how it might fall into our visual field.

But the words aren't meaningless just because we might disagree on some edge or corner cases.

The thing is, lots of people use words all the time without getting analytical about it. My daughter is 5 and knows what right vs. wrong is, but I doubt she could explain it to anyone without it just being circular.

When people use the words "right" and "wrong" (and all the related words such as good and bad and moral and immoral), most of the time they all pretty much agree with what it is. Stealing is wrong, cheating is wrong, killing is wrong. Helping someone who is hurt is right.

You can come up with scenarios where there are ambiguities, sure, just like with up and down, but most people agree on the basic ones.