Thank you, I’ll explain what I mean.
First, the example of cats was only an example, based on the saying of the Sages that had the Torah not been given, we would have learned modesty from cats.
The question is a principled one, not about a particular case.
Wikipedia gives several arguments that suffer from the naturalistic fallacy; I’ll bring one example:

A. Supporters of the theory of evolution maintain that the most well-adapted creatures survive (is).
B. The poor of the city will not survive the winter if we do not provide them with help (is).
Therefore:
C. One ought not help the poor (ought).

The fallacy says that you cannot derive the ought from the is, but if I assume that creation (aside from human action, since man has free choice) is not only existent but also proper, then this is deriving an ought from an ought.

I know the naturalistic fallacy very well. No demonstrations are needed for that. I still haven’t seen a question here.

My question is whether, in your view, the nature of the world is merely existent or also proper. And if your opinion is that it is also proper, do you disagree with this fallacy?

The nature of the world is as proper as possible. And within that framework there are different groups with different characteristics. When you want to learn something from the nature of the world, you have to decide whether to learn from the cats or from the dogs. So this has no implication whatsoever for our ability to learn from the world. And certainly all this has nothing whatsoever to do with the naturalistic fallacy. If I thought one could learn from cats, I would build the following argument: cats are modest (and there is no other animal that is not modest). The world is structured properly. Therefore, it is proper to be modest. That is not a fallacious argument but a fully valid one, since the second premise is not factual but a bridging premise between facts and norms.

The questioner assumes that there is a hidden premise that certain things ought to be upheld, but that itself is where the fallacy lies—where does this premise come from?!

A fallacy does not deal with the premises but with whether the conclusion follows from the premises.

Thank you very much indeed for the enlightening insights.
I’ll bring again the argument presented on Wikipedia as a naturalistic fallacy (ought from is), and I’d be glad to know whether, in your opinion, this argument is ultimately valid, since you too assume that the nature of the world is proper.
A. Supporters of the theory of evolution maintain that the most well-adapted creatures survive (is). (My addition: and that is what ought to be.)
B. The poor of the city will not survive the winter if we do not provide them with help (is).
Therefore:
C. One ought not help the poor (ought).

I don’t understand where all this is going. This formulation is very problematic and deeply flawed. But it can be refined into a valid argument. That is obvious. What is there to discuss here?!
A. The adapted survive.
B. Those who survive are worthy of survival, and those who don’t are not.
C. The poor do not survive.
Conclusion: it is not proper to be concerned for their survival.
And even this is not precise, because one can define collective survival (that is, survival through help from others is also fine. By the way, that is also true evolutionarily).
I think the hair-splitting has run its course.