The programming paradigm that organizes the software into functions is called procedural programming. For example, C is a procedural programming language. Most dynamic languages like JS or Python can be used in a procedural style.
While you are also organizing your code into separate files, there is no commonly used name that describes this. For example, modular programming is more about encapsulation than about using multiple files.
It is perfectly fine if you aren't writing classes. OOP is nice but is not always a good fit. For many problems, a procedural approach is great.