The core question of philosophy is: how to appreciate life? What is our responsibility? How should we act? These are vital questions. Everybody engages with them in some way. Everybody learns philosophy in some way, the vast majority of learnings have no explicit connection to any religion or philosophical writings. Real life teaches you philosophy.
This list, and the philosophy curriculum, has issues. For one, it's not the best way to learn critical thinking. It's better to learn math proofs. Truth tables, contra-positive, breaking things out into cases, induction. For two, western philosophy rarely provides actual answers. It asks more paralyzing questions than provides answers. Don't get me wrong, there are many beautiful things in many of the books - what I'm saying is that they don't equip you to recognize their value.. none of them give you the full picture. If you read these books, you will find that very few books will claim to present the full and complete truth. That's because they don't. They are incomplete.
I believe true philosophy is more psychological, pragmatic, and spiritual than most of the philosophy curriculum would teach you. What are thoughts? What is productive vs not productive uses of time? etc.
After I graduated with my minor in philosophy I read a book called Be Here Now. It discusses common aspects of many spiritual traditions. I also read some of the books in the bibliography of Be Here Now -- Tao Te Ching, some Hindu/yoga books, some Christian books. Today I am an Eastern Orthodox Christian. In Orthodoxy we understand Wisdom to be another way of talking about Christ. That's philosophy after all - philo sophia - love of wisdom. I can attest that the orthodox church has the fullness of truth and all the answers to any questions I have. It is the true philosophy.