What is real? There is something in us that simply "is" - constant and unchanging. Other than that which "is," there are various abstractions.

There is a Zen poem that says: "You cannot catch hold of it, nor can you get rid of it. In not being able to get it, you get it. When you speak, it is silent. When you are silent, it speaks." And the last two lines are the most important - ideas and concepts only complicate things. That's why philosophy is so bad at defining these phenomena - we can talk about it, but it doesn't make much sense.

Arthur Schopenhauer once summed up free will this way:

“Man can do what he wills but he cannot will what he wills.”

You put a lot of thought into this question. But we should always start with the basics. For me, the fundamental thing is to ask yourself the question "Who am I?" It's a tricky question, but without answering it, we will only dive into further nonsense of identification, including all the unnecessary thinking and ideas. Therefore, discovering who exists is the first part before we start discussing when. And as far as I know, once we discover the Who, the rest will be irrelevant.

Tao Te Ching
by Lao Tzu

Is there a unitary concept they share? — hypericin

They are part of the symbol system we have created for communication - abstraction.