If people stopped getting murdered, they’d still be killed by illness, parasites, old age, accidents.

So it's okay for me to murder, because those people would die anyway? If not, then there's no point in bringing it up.

If humans stopped eating meat, millions of animals would still be killed by predators, illness, parasites, old age, accidents

Just like there's no point in saying that, unless it's intended as some kind of justification.

Why is it OK for other animals to prey on other living beings, but not humans?

In other words, why should we hold humans to a higher moral standard than lions? Are you really asking that?

If so, I can give you an answer but it seems like a ridiculous thing to ask and I'm just about positive you don't actually believe that if the standard is good enough for lions and sharks it's good enough for humans.

but not humans?

Think about it for 30 seconds and I bet you can come up with two really good reasons why there should be a different standard. If you give up, I can tell you the answer but it's really obvious. I'm confident you can come up with them if you try.

to prey on other living beings

This is also reframing the problem in a weird way. Living isn't the same as having interests, preferences, emotions, being able to suffer, etc. The majority of people who are against (unnecessarily) eating animal products don't take that position just because animals are living, but because they're sentient.