The root fallacy is the fallacy of assuming the modern use of a word or phrase determines how it was used throughout history. Naturally, since language evolves over time, every language has its fair share of words whose meaning bears little to no resemblance of its original meaning. This includes English, a language which, in some cases, flips the meanings of words. "Bully", for example, used to be a positive term, meaning a fine person, or even a sweetheart, whereas today it refers to an unpleasant and antagonistic individual.
Most people are unaware of this archaic meaning, and there is nothing about the term "bully" that would even conjure such thoughts in one's head. But some words have roots that we instinctively know are unrelated. The word "turtle dove", for example, does not refer to a flying reptile with a shell. More obviously, pineapples are not apples, nor can they be found growing on pine trees. Guinea pigs are quite evidently not pigs, and are native to South America, not Guinea.
Most interestingly, an object's name may influence language as radically as language influences an object's name. Take, for example, the word "orange". The oldest record of "orange" being used to describe the color is in 1502. Before this time, however, orange was simply seen as another shade of red. This is why certain orange animals, such as the "robin red breast", retain their "red" names to this day. The reason for the switch is that when oranges were first imported into Persia and Spain, they received the name "narang", which became "pomme d'orenge" in French, and finally, "orange" in England. Thus, the color did not name the fruit; the fruit named the color.
With all of this in mind, we see just how silly the root fallacy is. Unfortunately, in many realms, people still use it. This includes the realm of religion. Biblically speaking, God created the heavens, the earth, and all that are in them in 6 days (Exodus 20:11), and this occurred roughly 6,000 years ago. Initially, there was no sin, and so there was no death, and all animals ate plants (Genesis 1:30). It was sin that brought death into the world (Romans 5:12; 1 Corinthians 15:21–22), which, contrary to certain interpretations, includes the death of animals (Genesis 3:14; Romans 8:22).
However, in an effort to fit atheistic creation narratives into Genesis, some point to the names of certain animals, most commonly the lion and the owl. It is alleged that in Hebrew, the names of these animals reflect their predatory nature, and since Adam is the one who named them this way before The Fall, they must have been predatory beforehand.
As we have already shown, this is absurd reasoning. In fact, with the explicit and clear teachings of Scripture, it's far more likely that Adam named the animals according to their peaceful, pre-fall nature, then post-fall, their names became synonymous with their newly developing violent tendencies.
This, of course, assumes a single one of the names Adam gave his animals survived the Babel event, in which God scattered the human race across the globe by confusing their languages. It is uncertain, and frankly unfathomable, that such an event would conveniently preserve all of Adam's name for the animals. Thus, to argue from any supposed meaning of their names in any language is ridiculous.
Ultimately, it stems from the same thing that brought death into the world in the first place: Sin. Sin looks for any excuse to stand in opposition to the explicit teachings of Scripture. The root fallacy is one more poor line of reasoning that pits rebellious human beings against our Holy God.