For a human being, to possess a consciously experienced first-person perspective means to have acquired a very specific functional profile and distinctive level of representational content in one's currently active phenomenal self-model: It has, episodically, become a dynamic inner model of a knowing self.

Subjectivity means to catch yourself in the act.

In ordinary life, the phenomenology of embodied emotions is an excellent example for dynamic changes between transparency and opacity: You can "directly perceive" that your wife is cheating you, or you can become aware of the possibility that maybe it is you who has a problem, that your "immediate" emotional representation of social reality might actually be a misrepresentation.

Speaking as a phenomenologist, it seems to me that a considerable portion of mind wandering actually is "mental avoidance behaviour", an attempt to cope with adverse internal stimuli or to protect oneself from a deeper processing of information that threatens self-esteem.

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.

Whoever loses the capability for inner silence, loses contact to himself and soon won't be able to think clearly any more.

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.