and we are all metaphysicians...

Metaphysics is one subject in philosophy that can be hard to wrangle a good definition for. The word "metaphysics" has itself a sort of storied history. Aristotle is credited with the oldest known writings we have on "metaphysics," yet he himself would not have defined this particular collection of writings as metaphysics. You may or may not know that a good chunk of what in Aristotle's day was considered "philosophy" would today be considered biology, general science, and physics. It was a translator after his death that dubbed the writings we speak of now as "ta meta ta phusika" which translates roughly to "the ones after the physical ones." Indeed these chapters did directly follow Aristotle's physics, as it happens they would become a subject all their own.

Enough jibber jabber. What IS metaphysics? A very broad generalization of metaphysics can be summed up in a very broad general question:

What exists?

Simple as that question is there are an infinite number of questions that can fit inside that tiny two worded question. For example:

Is mathematics an actual thing existing outside our understanding, or is it a thing we use to understand? Is time an actual thing outside our understanding or is is something we use to understand? Do I exist? Do you exist? What is qualia? Do animals experience qualia? Do i have a soul? Is there a god? Are there gods? Does the world exist as I perceive it, or is it affected by my perception? When/where did the universe start (and why)? Is time an actual thing outside our understanding or is is something we use to understand? What is free will? As I age and my tastes and knowledge change, do I change or am I the same? What is causality?

This is truly the tip of the metaphysical iceberg.

When we ask "what exists?" the "what" is the important part of the question. THERE ARE SO MANY WHATS!!! When people think of philosophy as a subject it is often metaphysics they think of instinctively.

why are we here?

Metaphysics is an exciting, storied, and extensive philosophical discipline.