I believe that if we would carefully apply the distinction between transparency and opacity to the different layers of the human self-model, looking at self-consciousness in a much more careful and fine-grained manner, then we might also arrive at a new answer to your original question: What a "first-person perspective" really is.

As a first-order approximation, I would say that phenomenality is "availability for introspective attention": Consciousness is a property of all those mental contents to which you can in principle direct your attention.

I could never understand how someone would embark on their life without having first confronted and clarified the truly fundamental questions.

What many people don't see is that there are abundant examples of phenomenal opacity: It is one of the most interesting features of the human conscious model of reality that, first, it can contain elements that are not experienced as mind-independent, as unequivocally real, as immediately given, and second, that there is a "gradient of realness" in which one and the same content can be experienced transparently or in an opaque fashion.

The Ego is a transparent mental image: You, the physical person as a whole, look right through it. You do not see it. But you see with it.

The notion of a conscious model of oneself as an individual entity actively trying to establish epistemic relations to the world and to oneself, I think, comes very close to what we traditionally mean by notions like "subjectivity".

The conscious experience of being a subject arises when a single organism learns to enslave itself.