The simple answer to your question is “No”. It’s not normal to be so isolated. Human beings are social creatures by nature. As much as you want to think you live in a universe of one, you don’t. Like everyone else in the world, you are dependent on other people in a variety of ways. Even a hermit needs other people to be a hermit from.
You’ve compensated for not being able to figure out how to get along by withdrawing from the social world. If you continue to live like this, it is going to have negative effects on both your mental and physical well-being.
So, as much as I think you are going to hate it, I do think you need to see a mental health specialist for an evaluation. You may be right that you are just a misanthropic individual but, even if that’s the case, it may be important to understand why. With that understanding, you can decide if you want to keep it up or change it. It also occurs to me that you may be on the high end of the autism spectrum. If that’s the case, your thinking and behavior may have come about as a compensation. There are better ways to deal with it.
You do have a talent for writing as demonstrated by your clear letter. But even the solitary task of writing is usually for and about other people. We have to live life in order to have things to write about.
I think you deserve better than you’ve got right now. Narcissus, the character in Greek legend and the person for whole narcissism is named, loved himself as you do and it caused his death. People are not meant to narrow their world and their love to only themselves. When they do, it results in a kind of mental atrophy and the world becomes a very lonely place.
I wish you well.