@KochengOren
Phew, I'm glad we can at least agree on that first part. 😀
Human knowledge is inherently incomplete. But science doesn't
need to know everything. Someone who says otherwise is probably either oversimplifying, or trying to pull a fast one.
In fact, it's not even what science is about. Science is taking observations, making predictions based on those observations, and then measuring how accurate those predictions were. The better the predictions, the better the model. Because there are no 100% certainties, rather than trying to achieve absolute truth, science is trying to
quantify doubt.
We have a incredibly high level of confidence in a lot of core areas, and like I said with the correspondence principle/classical limit, that gives us a pretty good idea of the limits of what we'll find.
With regards to sea serpents, if they existed, we will likely find remains eventually, assuming they weren't people seeing the tentacles of giant squid. Otherwise, we also have lots of examples of humans creating fantasy creatures from their imaginations. (I've played D&D, and I've read the Aberdeen Bestiary, circa ~13th century)
1) As for the Kraken, are you sure you don't mean the giant squid? The earliest descriptions of the Kraken say that it was crab-like in nature, see
The First Attempt at Natural History of Norway, Copenhagen, 1752. It was also claimed to be 16 km wide, which from what we know of crustaceans, would make it impossible for them to molt or support their internal structure with an exoskeleton above the water (cube-square law) to imitate islands as they were said to do in myth. Giant squid, however, have records documenting their existence as early as Aristotle (4th century BC), and have had physical evidence since at least 1861 when a ship of the French navy encountered one. (Which directly inspired the giant squid attack in 20,000 leagues under the sea)
2) We don't know how to handle corium, but that's not a science thing, that's a human politics thing. There are ways of handling it, like encasing it in a giant dome. It's not a question of scienctific theory, but of value judgements. "How much is it worth to do the thing." We know that we're not going to overturn thermodynamics, or change the half-life of an isotope.
3) When people want to figure out how the Higgs Boson works, they can spend some millions of dollars and build a particle collider. When people want to figure out how to treat diseases, they can't just grab a few thousand people off the street and start cutting them open. Even if it would make things go faster. (In the end, we know we won't be able to reverse entropy, and we have a pretty good understanding that cures won't involve homeopathy.)
We don't know everything, this is absolutely true. But we do know some things with pretty solid confidence, and we can use those things to make some reasonable predictions about things we'll find in the future.