My answer basically agrees with @Amadeus@Amadeus, but I want to emphasize the relation between fiction, nonfiction, and philosophy.
Nonfiction (science) writing is the farthest from fiction (obviously). Philosophy is not necessarily nonfiction. In some regards, philosophy is like fiction, ie. what axioms are assumed come from one's thoughts/beliefs much like purposeful fiction. Of course, philosophy is more about logical reasoning than telling a story and philosophy is meant to answer questions (or more specifically, provide a possible answer based on assumptions and logic).
Something to note is that good fiction also obeys logic through world building and character building. Writing quality logic in non-fiction works can improve your fiction writing logic.
So philosophy provides possible answers through logic. Philosophical essays typically use a formal structure and direct logic, but not always (Heidegger was very poetic in his writing, and there are also dialogues, such as Plato's works, that express the reasoning in more of a story formatthrough dialogues).
As @Amadeus@Amadeus said, fiction is for entertainment. Whether that entertainment bringbrings joy, sorrow, or whatever doesn't matter. It's still entertainment. I'll read and enjoy plenty of tragedies if they move me and expand my horizons.
That last partsentence is what I want tothe focus on hereof this answer. There is a connection between philosophy and fiction, or at least there can be. For me, I love stories because it introduces new concepts into my life and I witness characters interacting in ways I may not have seen people do so before. It increases my awareness of certain things, inspires me, and teaches/reveals things too. Philosophy accomplishes the same goals for me as well: I learn new concepts, thinking/reasoning patterns, and understand how people think.
Good fiction, imho, not only entertains but also carries a message. That message is either in part or entirely a philosophy. You could think of fiction as a different way of expressing philosophy. Some philosophers were artists/artistic, ieartistic (ie. Heidegger found poetry best for expressing ideas and Plato valued dialogues).
There are many nonfiction people who write or do art, and so I would not worry if I were you. All of these things simply take practice and understanding. Another example of one who has dabbled in all of these things is myselfpractice and understanding.
I have written nonfiction scientific articles, philosophical essays, and fiction, and I also enjoy drawing/sketching and making music. Granted my works are not the greatest, but practice makes perfect. I am certain you could write great fiction as well as other works.
You state you fear becoming a critic. Now, this reallyThis depends on what you mean by that, but in my opinion, I believe good writers and artists are and should/should always be critics. By critic here, I mean a constructive critic. One with a good eye in the craft to spot what nuances affect certain things, like the affect of word choice or including a scene in a story. You do not have to be a critic in the negative sense where you either look down at other's work or tear people's choices apart mercilessly. Given your fear of being a critic and if that negative connotation of critic is what you mean, then I doubt you'll become that. I also encourage you and every writer to seek and give constructive criticism. It helps all parties involved grow to be better writers and to understand the craft more.
tl;dr
tl;dr
You can most definitely write philosophical essays, nonfiction works, and fiction. I have done so, as have others who have donewritten more and admittedly with better quality in all 3 types than myself. To write works you are proud of and that others appreciate will take practice. Always seek and give criticism to improve your writing and understanding.
Also, these writing types can overlap. Fiction can be used to express philosophy and also teach nonfiction (ie. commerce, science). Of course there is varying levels of coverage and quality, but it is still possible. Writing in one will help to some degree in writing the others.