I don’t think types were hard originally, but rather the popular typed languages for a very long time were C, C++, and Java and they were loaded with foot guns, or at least the popular advice encouraged you to use those languages in a very difficult to maintain way (e.g., shoehorning inheritance into every problem in C++ and Java) or else they were ergonomic problems (lack of type inference or good tooling). The dynamic languages didn’t share these foot guns, so people wrongly assumed they were type system problems.