This is completely normal! If you've been writing daily for the past few months and you're finding yourself unhappy with your first work, there is no doubt that you have simply improved your writing. That's good! It might make your story feel a bit wonky to you, but that's okay. Personally, I have only posted one story so far. When I first posted it, I was quite happy with it. Now, every time I think about it, I get an eh feeling. In my eyes, it is not a masterpiece and was never created to be that way. I created it because I wanted to see what I could do, how I build stories, characters, personalities, relationships, etc.
I now have two more stories unposted and in the works. Already, I feel they are better than my first. I'm improving! My stories are growing. You should look at your earlier works as your babies. They are yours, they helped you grow, and they are shaping the writing you will become pleased with.
An example of this that is easier to see because it is done through drawings, but think of the manga Haikyuu! If you look at Furudate's beginning chapters and compare them to the chapters nearing the end, you will see a massive improvement and development in his style. He is not redoing his beginning chapters nor is he upset with them. They helped him grow! Not that I know him personally, but I'm sure he is very proud to look back and see his steps of growth. Think of it like keeping baby photos.
I always say that while drawing is a form of art that changes over time and depends on the person, writing is no different; writing is a form of art and people have different forms. Unless you are grammatically incorrect, your writing is not wrong but simply your own.
