Morality

You're on the right track here. It's a metaethical claim, not a moral one.

Yeah I don't understand the point the meme is trying to make

You could argue that moral relativism is a metaethical thesis and so is not straight away self-defeating. Even so, moral relativists often go on to claim that we shouldn't judge the moral acts of other cultures based on what we take to be universal moral standards. Because, get this, it would be wrong to do so.

Except table manners. Those are dictated by the Universe itself!

Nobody exists on purpose, nobody belongs anywhere, everybody's gonna die.

Come watch TV?

Welcome to every discussion on every digital medium that's ever existed?

Does it really play ball in the context of metaethics?

I'll define morality and ethics as a normative system (operating on different levels of abstraction, with different targets as their focus, but maintaining the same kind of interaction) emergent from imperfect information transmission between any two points in space-time, i.e. the same body at t=n, t=m; or two different bodies at the same time (just to account for quantum stuff) which occur at level of complex life. I'll say life is any system with the capacity to maintain or decrease entropy (Schrödinger is where I first saw this) for some period of time, and intelligent life meets some threshold for delay or non-direct determinants of information from outside the continuous body to manipulate its environment to a lower entropy state, one which does not as of yet have the same quality of decreasing or maintaining entropy as the intelligent lifeform does.

In this case, metaethics is a distinction in the realm of a type of interactions yet still a part of them. It's like one pizza, you can cut it in half and say you have a left half and right each belonging to the meta and non-meta partitions. Or you can say that what we regularly refer to as morals or ethics is simply the toppings, metaethics is the dough which is frankly too frequently ignored in discussions of ethics and pizza-quality. The dough similarly provides the framework or support for the toppings, without which you would have a spread out cheesy and saucy salad (if veggies are a topping, otherwise you have what I make in the middle of the night when I don't want the microwave to sound off to warm up food that would fill me up) which couldn't be characterized as pizza.

Sorry I think I changed topic there, I hope some of the point comes across.

Thanks, I appreciate the sentiment. I'm still going to take a pause on the philosophy memes as I literally can't stop myself from arguing in the comments and I should be working lol

At least the logical positivists where philosophically rigorous enough to drop the view when they realized it's untenable.

Universal moral truths. Like absolutes. We can say killing is bad, but many would say killing a mass murderer currently on a murder spree would be more moral than letting them kill a bunch of people.

There’s a fundamental misunderstanding here that seems suspiciously like a bad faith argument.

Just because there aren't moral truths doesn't mean a serial killer did nothing wrong. You seem to be stuck on finding a single contradiction and using that to dismiss everything else related as irrelevant. That's not actually how the world works.

Similarly in physics, the existence of non-newtonian fluids, doesn't invalidate Newton's work in fluid dynamics.

If there are no moral truths, then serial killers have done nothing wrong for example

This does not follow from moral relativism. Moral relativism simply states the morality of serial killers is determined by people rather than an absolute truth.

For example, if you add the detail of “serial killer of humans”, most societies would deem that morally wrong. In contrast, “serial killer of wasps” would be considered perfectly fine by many. A moral relativist would say the difference between these two is determined by society.

You can, of course, claim that murdering humans is not morally wrong. A moral absolutist might say “you’re wrong because X”, while a moral relativist might say “I don’t agree because X”.

Sure, and how does your understanding contend with the concept of a serial killer of Nazis? Or a capitalist?