We have already improved some things by using React patterns. You should do some homework and introduce those patterns wherever possible.
When writing applications, one key objective is to keep them modular and readable, but also as understandable as possible. It is always hard to tell when splitting code up is useful, and when it overcomplicates things. This is something that you will learn more and more about by writing as many applications and as much code as possible.
Let's begin to structure our application further.