FWIW it's objectively false that numbers are a system humans created. That's almost certainly true for symbolic numbers and therefore large numbers ( > 20). But pretty much every bird and mammal is capable of quantitative reasoning; a classic experiment is training a rat to press a lever X times when it hears X tones, or training a pigeon to always pick the pile with fewer rocks even if the rocks are much larger (i.e. ruling out the possibility of simpler geometric heuristics). Even bees seem to understand counting: an experiment set up 5 identical human-created (clearly artificial) landmarks pointing to a big vat of yummy sugar water. When the experimenters moved the landmarks closer together, the bees undershot the vat, and likewise overshot when the landmarks were moved further apart.

And of course similar findings have been reproduced etc etc. The important thing to note is how strange and artificial these experiments must seem for the animals involved - maybe not the bees - so e.g. it seems unlikely that a rat evolved to push a lever X times, it is much more plausible that in some sense the rat figured it out. At least in birds and mammals there seems to be a very specific center of the brain responsible for coordinating quantitative sensory information with quantitative motor output, handling the 1-1 mapping fundamental to counting. More broadly, it seems quite plausible that animals which have to raise an indeterminate number of live young would need a robust sense of small-number quantitative reasoning.

It is an interesting question as to whether this is some cognitive trick that evolved 200m years ago and humans are just utterly beholden to it. But I think it requires jumping through less hoops to conclude that the human theory of numbers is pointing to a real law of the universe. It's a consequence of conservation of mass/energy: if you have 5 apples and 5 oranges, you can match each apple to a unique orange and vice versa. If you're not able to do that, someone destroyed an apple or added an orange, etc. It is this naive intuitive sense of numbers that we think of as the "platonic concept" and we share it with animals. It seems to be inconsistent and flaky in SOTA reasoning LLMs. I don't think it's true that LLMs have stumbled into a meaningful platonic representation of numbers. Like an artificial neural network, they've just found a bunch of suggestive and interesting correlations. This research shows the correlations are real! But let's not overinflate them.