There's a video from Gary Bernhardt called Functional Core, Imperative Shell which made sense to me. These paradigms can work well together. OOP can be great too, the Ruby language is deeply OO and the core library is rich and OO. You can also only use hashes and arrays and type them with Typescript, using functions, types and namespaces and duck-typing, instead of classes and methods.

ps: closures are worth thinking about, we use them without even thinking about it