The first ancient Greece philosophers thought that Fundamental Reality is one of the basic physical elements, like air, fire, water and earth, or all of them together.
Their offspring, the atomists, thought it is “matter” or “atoms”
Others have thought that it’s “energy” or “forces.”
Or maybe its a combination of matter and energy working together. Maybe matter and energy are just two aspects of the same reality, so that we get the hyphenated word “matter-energy.” When we think of prime reality as particles we call it matter. When we think of prime reality as energy we call it waves. So maybe it’s both-and, not either-or.
At the opposite end of the spectrum from the atomists are the idealists who think Fundamental Reality is, well, Thought, various called Idea, Form, Mind or Consciousness. Some have envisioned a single, universal transcendent Mind, whether personal (God) or impersonal (Godhead), or both. Others have envisioned many finite gods. Still others have imagined that there are many subsidiary and differentiated Minds or Monads, centers of sentience and/or conscience, even hundreds of billions of them throughout the galaxies, but that all of them are ultimate absorbed into the One Universal Mind.
Still others have thought that Matter and Mind are two different realities that have little or nothing to do with each other. Matter is the realm of immanent physical quantities. Mind is the realm of transcendent spiritual qualities. This view is known as metaphysical dualism. Descartes held this view..
And then there are those who think that Fundamental Reality is a synthesis of Matter and Mind, again two aspects of a single entity. So both sides are right, but there is one reality, not two. This view is called Neutral Monism.
Aristotle thought that Fundamental Reality is Being, and that Being is composed of Matter and Form, not either one separate from the other. This view is called hylomorphism.
In more recent times some have suggested that Fundamental Reality is Matter-Energy + Form-Process + Body-Mind + Identity-Relationships. Obviously this group is trying to have it all, to say “Yes, you’re all partly right” to many difference theories concerning the nature of Fundamental Reality. Both-And thinkers like it. Either-Or thinkers hate it. Both sides believe that reason and the evidence support their view and contradict the other.
It is not likely that this ancient and ageless philosophical question will go away any time soon. And it is equally unlikely that there will ever be anything like “universal consensus” when it comes to answering the question. It will remain a Mystery we continue to live with, even while there will be strong partisans who hold their views, some provisionally and others with evangelistic zeal. Materialists, Idealists, Dualists, Panpsychists and others will continue to probe the Mystery as if it were a philosophical or scientific problem that can be solved by our finite and conditioned but promethean and inquisitive human minds. Whether it can or will be “solved” remains an open question. I have my doubts.