Don't think it's useless to take part in anything. In fact, any activity is worth taking part in. Especially for college students, learning is important, but practice is also very important. It is precisely because you have never participated in a painting competition that you should participate, from which you can learn something you don't know.
Many things are the first time, of course, you will feel nervous and insecure, but you still have to bite the bullet and do it. This is the embodiment of the value of life, but also a challenge. Don't be afraid of things, or you will live in your own world forever.
I especially wanted to learn piano in primary school, but I didn't attend because of my study. Now I regret it, so you must not let yourself regret it. Only after you do it can you understand the truth.
I remember when I was in junior high school, there was an activity in our school to give a speech on "Chinese Dream, My Dream". At that time, no one signed up in our class, and then the teacher forced several of us to go. Finally, I won the first prize and got the reward I deserved. From then on, I understood the truth. If you persist in doing many things, you may succeed. If you don't do it, you are doomed to fail.
Whether you like it or not, try it. Only good for you. Believe in yourself, come on!