Dynamic typing and static typing can coexist in the same language. C# is generally statically typed, but the more recent versions support the dynamic keyword - at which point you're statically typing things to be dynamically typed. Typescript of course goes the other way - adding static typing features to otherwise dynamically typed Javascript.

...the first thing I do when encountering JSON in TypeScript these days is to add type definitions to describe the schema. If I have a hard time describing the schema to TypeScript, I'm going to have an even worse time trying to keep it straight myself.