If Samsara is natural in origin, is the Wheel of Dharma artificial?

Eventually, beings figured a way out

Transmigation is beginningless. Therefore you should not assert that in a general sense there was a past where nobody knew about the deathless and that someone eventually figured it out.

At any given point in history you will find this knowledge and if nobody there & then knows, then you will find someone who knew if you go far enough back.

Added;

Beings are & are of nature, they are part of the world, per definition. If anything 'beings' are nature conceiving & perceiving nature in nature 🤪

Whatever intellect is found in nature that is nature's intellect, there is no other intellect that isn't part of nature.

To me the expression 'Buddha taught only nature and the cessation of nature' is quite agreeable.

I imagine that Nibbana is natural and the default state and that samsara is the unnatural created state that somehow existence has got stuck in. Of course the wheel of dharma is artificial in the basic sense that it is a concept.

Evolution in nature perpetuates samsara because it encourages becoming and it encourages reproduction. From the sutta quote below, you can see that going with the flow stands for craving. Craving is the cause of suffering according to the second noble truth. Evolution drives the natural tendency towards craving - sensual cravings and cravings towards becoming.

Going against the flow of nature is renunciation. Trying to end craving is against what evolution in nature drives us towards.

The idea of natural spiritual evolution is not found in Buddhism. The effort to becoming liberated is against natural evolution. Furthermore, as you can see in the Buddhist world today, extremely few join the monastic order in pursuit of liberation.

Natural intellectual evolution only leads towards increasing sensual enjoyment while attempting to reduce suffering, through improvement in healthcare, education, infrastructure, politics and economy.

Natural intellectual evolution does not lead towards liberation from clinging to sensual enjoyment. Rather, it leads one towards asking how to increase enjoyment while avoiding suffering as much as possible.

This was said by the Blessed One, said by the Arahant, so I have heard: "Suppose a man was being carried along by the flow of a river, lovely & alluring. And then another man with good eyesight, standing on the bank, on seeing him would say: 'My good man, even though you are being carried along by the flow of a river, lovely & alluring, further down from here is a pool with waves & whirlpools, with monsters & demons. On reaching that pool you will suffer death or death-like pain.' Then the first man, on hearing the words of the second man, would make an effort with his hands & feet to go against the flow.

"I have given you this simile to illustrate a meaning. The meaning is this: the flow of the river stands for craving. Lovely & alluring stands for the six internal sense-media. The pool further down stands for the five lower fetters. The waves stand for anger & distress. The whirlpools stand for the five strings of sensuality. The monsters & demons stand for the opposite sex. Against the flow stands for renunciation. Making an effort with hands & feet stands for the arousing of persistence. The man with good eyesight standing on the bank stands for the Tathagata, worthy & rightly self-awakened."
Iti 109

Also please see this answer.

So the wheel of Dharma was arficial, but at such scale and ingrained in the very fabric of the Universe that it could pass as a force of nature. The only difference is that it must be "kept spinning" by illuminated beings.

It could be either way depending on context. It's "artificial" in the sense that each individual after hearing the precious Dhamma must actively put in the real work to constantly improve upon themselves in order to make progress. But by the same token, it's also legit to say that it's also "natural" too. Like the yin-and-yang of the universe, if Samsara exists as part of the natural order of things, then the way out of it would also naturally exists. The Buddha himself certified that He did not invent anything novel all by himself. Instead He simply re-discovered the Path many of His predecessors had already discovered, and the torch will continue to be carried on long after the passing of Gotama Buddha, with the future Metteyya Buddha and others long into the future.

“Suppose, bhikkhus, a man wandering through a forest would see an ancient path, an ancient road travelled upon by people in the past. He would follow it and would see an ancient city, an ancient capital that had been inhabited by people in the past, with parks, groves, ponds, and ramparts, a delightful place. Then the man would inform the king or a royal minister: ‘Sire, know that while wandering through the forest I saw an ancient path, an ancient road travelled upon by people in the past. I followed it and saw an ancient city, an ancient capital that had been inhabited by people in the past, with parks, groves, ponds, and ramparts, a delightful place. Renovate that city, sire!’ Then the king or the royal minister would renovate the city, and some time later that city would become successful and prosperous, well populated, filled with people, attained to growth and expansion.

“So too, bhikkhus, I saw the ancient path, the ancient road travelled by the Perfectly Enlightened Ones of the past. And what is that ancient path, that ancient road? It is just this Noble Eightfold Path; that is, right view, right intention, right speech, right action, right livelihood, right effort, right mindfulness, right concentration. I followed that path and by doing so I have directly known aging-and-death, its origin, its cessation, and the way leading to its cessation. I have directly known birth … existence … clinging … .craving … feeling … contact … the six sense bases …. name-and-form … consciousness … volitional formations, their origin, their cessation, and the way leading to their cessation. Having directly known them, I have explained them to the bhikkhus, the bhikkhunīs, the male lay followers, and the female lay followers. This holy life, bhikkhus, has become successful and prosperous, extended, popular, widespread, well proclaimed among devas and humans.” ~~ SN 12.65 ~~