A timid and shy cat is not a ”helpless cause” and there is several ways to change this behaviour so that both you and your cat can live closer together.

First of all, you as the owner need to be patient with your cat, because it will probably take some time and effort from your part, and every little mistake can possibly set you back a few steps in the progress. If you already know that you are not up for it, I would suggest that you find a loving home for her that will know from the start that this cat need some help, and refer this person to this text. To rehome her now might be the best for her if you don´t have the time or patient to do this.

First we deal with the ”why”
There could be a lot of reasons why the cat is shy, and sometimes it is impossible to know exactly why, but it is valuable to know how a cat can turn out this way.
If the cat came from the streets or were taken too early from it´s mother and siblings, the result can be that this cat got interrupted in the development of the behaviour, right at the age where it is so important for a kitten to know what is right and wrong. A kitten at the age of 12 weeks should have a warm, loving home to look forward to, where she will be smothered with love and affection. On the streets, this kitten will not have the essential elements for development, like playing to learn how to defend herself, and sometimes not having the possibility to hunt and eat, and would thus not get the strenght to do anything else but to hide from the most emediate fears. Humans are the highest of threat here because she have never encountered the human as a kind being. The domestic cat need humans to care for them in a human world, and the sooner they know that we are here to help them, and love them, the earlier they will trust us and give their love back.

Things that can make your cat shy after living in your home for a time, or even years
As a kitten moves in to your home, she will experience new smells, new surroundings and new humans. This is both exciting and a bit scary for any cat, so it is your responsibility to make the move as good as possible for the kitten or cat. Let her know that all humans in the new home is kind, and let them meet her one at a time, especially if you have kids because it can become too much for the cat to meet all at once that wants to pet her. If you see that she reacts to high voices already, then tell all humans in your family to have a lower voice the first few days, it will make the transition much easier.
Cats need places to hide, it is in their nature and it will not make the less timid to take away those hiding places, it´s quite the opposite. Have lots of places both lower to the floor and higher up on shelfs, in high cat scratchers and maybe just throw a blanket on your bed if that is a room away from the household noices. The cat will go to these places to calm down and do not follow her there right away, visit her there when she have been there for a while. Examples for hiding places on the floor might be a cardboard box placed in a corner somewhere she can still have her eyes on all of you, but feel secure.

If you suddenly realize that your cat only reacts in a bad way when one of you speaks or raise your voice, then tell that person to lower his or her voice for a while at home, and gently approach the cat with treats or just let him or her drop treats nearby the cat so that she will slowly know that this person is no threat. Let this person give her food for a few days, and everything possible to associate the person with positive experiences.

Changes in the living situation can make even the most affectionate cat a bit unsure, such as redecorating, someone moving in or a new familymember (cat, dog, baby) so if you just have the cat in mind as these changes occur, you will probably make things a lot easier for both you and the cat.

To get a hormone diffuser whenever you know there is something changing at home is a good way to go and will help your cat to calm down even during these changes.
Go to Feliway´s website to read more and find a retailer near you (most pet stores sell these today)

and for now, don´t punish this cat when she´s doing wrong, it will do more damage than good