Things happen fast! One year ago I was a Junior Developer building a really small gem for Ruby on Rails sort_n_params, my first contribution as a developer to the open source's scene.
If you have an idea, build it up. Ask for help from your colleagues if you're stuck -- it doesn't matter if your idea sounds silly or small, building and finishing things helps us improve our skills.
The solution you have found may be useful to others, so share it. Maybe someone else will help you improve your solution. Don't be shy!
Maybe you're looking for your first job in the industry, but a lot of interviewers ask you about previous experience. Having your own project published in Github or deployed in Heroku will help you prove that you already have some experience with coding.
Technology is advancing rapidly and it is very possible that our code will change in the near future. Testing our code prevents problems and saves time and setting up a continuous integration service like TravisCI to our repository ensures the proper functioning of our project.
It doesn't matter if you only make a small contribution, it will help you improve and meet a world that is growing every day
Don't be scared! If you want to publish a new gem, there are plenty of tutorials on the web and it doesn't take long to do so.
I hope my experience encourages you to make your own gems and projects. Let's code!