Subjectivity means to catch yourself in the act.

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.

I believe we should really take our own phenomenology more seriously. What a good theory of conscious must explain is the variance in this subjective sense of realness: There clearly is a phenomenology of "hyperrealness", for example during religious experiences or under the influence of certain psychoactive substances.

Of course, I strongly sympathized with Habermas and the philosophers representing the Frankfurt school, but I also saw the lack of conceptual clarity, and perceived the not-so-revolutionary self-importance in the epigones of Horkheimer, Adorno, and Habermas.

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.

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

I believe that gut feelings, the sense of balance, and spatial self-perception are so firmly coupled to our biological body that we will never be able to leave it experientially on a permanent basis.