If you have a desire to write, do it. It won’t be perfect. It will need work. That’s how all books start. You refine it after it’s down on paper. The story will probably change from what you first envisioned. This is a good thing.
There is no mystery to writing. You get better as you go along. Read different genres. Be curious. Jot down ideas when they strike.
Perfection is a wonderful thing, but with writing, it’s not required, needed, or expected.
One person’s opinion is just that. One opinion. Don’t let criticism hold you back. Sometimes people are jealous of others that go after what they want. Know the difference.