#I need a source for that extinction overhunting fact
"50 years" is more a rough simplified estimate than an actual timeframe, but yes, up until the extinction of the great auk, many humans genuinely didn't believe their god would let one of his creations go extinct. I can only really speak on the perspective of Western (predominantly Christian) scientists, but it was widely believed that extinction was simply impossible. You have to remember that the theory of spontaneous generation wasn't definitively disproven until the mid-1800s.
Allow me to quote wikipedia for a second, because the editors did a great job of summarizing this worldview:
Prior to the 19th century, much of Western society adhered to the belief that the world was created by God and as such was complete and perfect. This concept reached its heyday in the 1700s with the peak popularity of a theological concept called the great chain of being, in which all life on earth, from the tiniest microorganism to God, is linked in a continuous chain. The extinction of a species was impossible under this model, as it would create gaps or missing links in the chain and destroy the natural order. Thomas Jefferson was a firm supporter of the great chain of being and an opponent of extinction, famously denying the extinction of the woolly mammoth on the grounds that nature never allows a race of animals to become extinct.
Similarly, in 1695, Sir Thomas Molyneux published an account of enormous antlers found in Ireland that did not belong to any extant taxa in that area. Molyneux reasoned that they came from the North American moose and that the animal had once been common on the British Isles. Rather than suggest that this indicated the possibility of species going extinct, he argued that although organisms could become locally extinct, they could never be entirely lost and would continue to exist in some unknown region of the globe. The antlers were later confirmed to be from the extinct deer Megaloceros. Hooke and Molyneux's line of thinking was difficult to disprove. When parts of the world had not been thoroughly examined and charted, scientists could not rule out that animals found only in the fossil record were not simply "hiding" in unexplored regions of the Earth.
Of course there were naturalists proposing the concept of extinction as early as 1796, but a proposal of a concept is not the same as widespread societal acceptance of a concept.
Someone in the comments of this post brough up the dodo bird as an example of a more recently extinct animal that 'proves' that humans ought to know about extinction. After all, there were written accounts, paintings, and even body parts to prove its former existence.
But to that I raise you the Jenny Haniver:
Jenny Hanivers are skates or rays preserved to look like dragons or devils. They've been sold as hoaxes since at least the 1500s, and naturalists have warned people of their fraudulent nature for just as long. People knew about hoaxes and misrepresentations. We've all heard the story of how the first platypus body to reach London was thought to be a clever hoax.
By the 1700s, one taxidermy dodo was known to exist. It was donated to the Oxford Museum, which burned it in 1755 because it had decayed considerably, meaning it was unfit for study and display, plus it was putting their other taxidermy specimens at risk. Taxidermy back then mostly just involved drying the skin on a base without preservatives, leaving the specimen vulnerable to pests and fungi. Only the mummified head and foot were saved and thrown in a drawer where they were more or less forgotten about.
So by the year 1800, naturalists had no evidence that the dodo was real, and enough evidence that it was a fraud. According to "Panati’s Extraordinary Endings of Practically Everything and Everybody" (1989), p. 203:
Only a hundred years after the dodo was officially declared extinct, Europeans refused to believe such a fantastical creature had ever existed. It became a myth like the unicorn. By 1800, professional naturalists were casting doubt on written descriptions of the bird, as well as on extant drawings, many of which did display striking inconsistencies. It became scientific vogue to deny the bird’s existence and to challenge the Oxford head and foot as fakes. Why, skeptics asked, had no one preserved a skeleton? Unless there had never been a dodo. Skepticism was so strong by 1850 that a group of zoologists journeyed to Mauritius in search of dodo bones.
Dodo bones wouldn't be discovered on Mauritius until 1863, but even after the dodo was proven to have existed, people still needed to be convinced that it's extinction was 1) a total extinction, 2) not a fluke, and 3) preventable.
By 1830, naturalists were aware that the great auk could soon be extinct (at least locally), but instead of calling for the protection of great auks, they called for specimens to be collected while they still had the chance. Conservation of a dying population was simply incoceivable to them. The last two known great auks were killed by an ornithologist in 1844.
It wasn't until the mid-1800s that extinction was really understood as a possibility, and it wasn't until the early 1900s that the conservationist movement as we know it took form. This was thanks in large part to everyone's favorite rampantly racist anti-indigenous animal lover, Theodore Roosevelt, who laid the groundworks of the Migratory Bird Treaty Act, and created wildlife preserves and national forests out of land stolen from Native Americans (but that's a story for another day).
Prior to the mid-1800s, we lost the mammoth, aurochs, European wild horse, moa, dodo, passenger pigeon, Steller's sea cow, Malagasy hippo, great auk, quagga, bluebuck, Falkland Islands wolf, huia, and many more megafauna, as well as countless rodents, bats, marsupials, and subspecies due to overhunting. We have lost many species since, but very few were due to malicious/targeted hunting. Most were due to ignorance, carelessness, or desperation. And every megafauna extinction has been fought by a conservation movement that is now, more often than not, succesful.
And there are signs, like the Lord Howe Islands stick insect, that soon enough it won't just be megafauna who reap the fruits of conservation efforts. A zoo near me is paying a guy to breed the critically endangered Desertas wolf spider. It doesn't get much less "charismatic megafauna" than that. And its extinction would weigh no lighter on the Earth than that of the mammoth.
