In ancient times, the elemental categories were cut and dry, representing only what their name implied. As societies spread and cultures exchanged information, it was discovered that, while everyone shared the belief in the pantheon, not everyone's definitions of what the gods represented were the same. The elements' definitions expanded to compensate. "Earth" started including animals as well, "fire" the art of war, "wood" agriculture, and so on. This also resulted in the common belief that the subjects of the gods' domains were composed entirely of their associated element alone.
Some elements' domains now included occupations, such as blacksmiths or farmers. Did this mean everyone of that vocation was also that element? Could they call upon that element, regardless of race? Resultant studies surprisingly revealed that, in actuality, every Rixilian had the potential to learn magic of any element, regardless of race or job. Researchers reluctantly concluded that each person must possess all ten elements natively; their race was simply a reflection of the one that expressed itself the most. Humanity was special in this sense, and everything else in the world was still under the jurisdiction of one element only.
While this definition was accepted for a time, the students of a new era of philosophical study brought scrutiny to this model. Are plants, under "wood," and animals, under "earth," not alive in the same way humans are? They seemed to have life cycles all the same; could they be composed of multiple elements too, or were they somehow lesser? Scientific advancements like the microscope, combined with modern magical research techniques, revealed that the elemental composition of most things was actually quite complex.
Modern theory now states that every element is present in all organic matter. It is the amount of each element, as well as how they interact together as one unit, that defines one thing from another, akin to molecular structure. The "elemental composition" of something is a property of its matter, rather than the equation of its very existence. Things are not created from an element out of a void, rather, things, objects, people, etc. develop specific elements within them as they grow and change. "Physical affects metaphysical" became a common way of shortening this idea.
These concepts, established within just the past 200 years, have helped pave the way to a better understanding of the natural world. This simple change in thinking revolutionized several fields of study. Medicine was no longer about adjusting so-called "elemental imbalances," and psychology gained ground as its own topic. Animal rights became a movement. Magic became highly experimental, pairing with industrialization to create the first pieces of magitech. The entire tangible world now had elemental properties one could discover and study, instead of just strict, singular categorizations.
While the pantheon itself cannot be truly studied, a popular extension of this theory is that the only things purely, singularly "elemental" might just be the gods themselves, and it's this quality that gives them the power of creation. Regardless what the truth may be, magic and science in Rixile march ever onward--who knows what could be on the horizon, just waiting to be discovered?