@Bizet : I 0% agree : “principe of sufficient reason” is an abstract, language focused, idealistic object belonging to foggy epistemological discussions between institutional bureaucrats of thought and it say nothing about the “we” reality your question was about.
“We” are real thing, a species. I upgraded this biological fact to the metaphysical level and could answer a precise answer : “we” are the metaphysical carrier or the category of Thought, as DNA is the carrier of Life etc. I also said I could go much further in the evidence.
You are not interested by this precise answer because you are not interested by the question : you are interested by the sensation that “we” is a mystery, the infamous Hegel’s night : you want mystery, you want transcendance, that’s why a precise answer does nothing to you.
Sorry but I am a metaphysician, I answer questions (I think I could provide deep mystery if explicitly asked for btw…)
This desire of mystery is the typical idealistic thinking abdication coming from the faulty [nature-human] bi-categorical immanent framework of Philosophy, as explained in my first post in this beautiful TPS forum : Breaking the [Nature-Human] bi-categorical framework of Philosophy