Legitimacy of cryptozoologist and creationist claims regarding certain cryptids

When one hears a cryptozoologist or creationist discuss supposedly "living" fauna that have been known to be extinct for a long amount of time, such as dinosaurs or plesiosaurs, there are often taxa that could serve as a significantly more plausible explanation for these creatures, or they disregard this explanation and many others, such as cases of misidentification, myth, or the ever-present possibility that the person making the assertion that these cryptids are real is simply making shit up.

Classics
One such cryptid that is often touted as being a "late-surviving hominin" is Bigfoot, but let's leave aside the fact that the extent of the distribution of Neanderthals across the globe was limited to Eurasia, specifically Europe, Western, and Central Asia and no hominin before modern humans ever set foot in the Americas according to the archaeological record, how exactly would a population of such large creatures go unnoticed for so long, especially in a region as densely populated as North America? The more likely explanation is that the supposed "sightings" of Bigfoot were a combination of misidentified animals (such as the American black bear, which is about the proportions of Bigfoot and can stand bipedally, and has foot proportions suspiciously reminiscent of supposed Bigfoot tracks ) and hoaxes.

Another example would be the so-called "Lake Champlain Monster", or "Champ", which is commonly cited as an example of "living plesiosaur", never mind that plesiosaurs went extinct with the dinosaurs, but when did anyone ever let reality get in the way of their fantasies? One animal that could be mistaken for a sea serpent that does inhabit Lake Champlain is the lake sturgeon, a type of fish that looks almost prehistoric and can get very large. It is easy to see how someone from a distance could mistake a lake sturgeon for a sea monster.

Dinosaurs
Sometimes creationists and cryptozoologists will assert that dinosaurs are still alive (besides birds, who don't count in creationist eyes as "dinosaurs"), and they will cite the cryptid Mokele-mbembe as "proof" that dinosaurs are still around. One should note that depictions of the Mokele-mbembe don't resemble modern depictions of sauropods, but rather out-dated ones, specifically the notion that sauropods were semi-aquatic swamp dwellers. One should also note that the vertebrate fauna of Africa, rather than being "prehistoric", is as modern as the rest of the world, and there are plenty of currently living African megafauna that can match the description of the Mokele-mbembe far better than a sauropod can, like rhinos, elephants, or hippos for instance.

In conclusion
Does it even need to be said? It's painfully obvious that creationists and cryptozoologists, in their monomaniacal obsession with proving their fantasies right, have ignored many lines of evidence showing that what they believe to be true isn't necessarily true, and will ignore all evidence to the contrary. This is known as a confirmation bias.