Sadly, that is the reality of Ruby, no excuses. Introducing static typing to Ruby is a huge task considering the way the language is designed.

The attempts you've seen is probably Sorbet (sorbet-runtime) and RBS. In my opinion, RBS would be an option for me if they didn't force me to work in a separate file just for type declarations.

There is one gem that is interesting, it reminds me a lot of jsdoc. It's called rbs-inline https://rubygems.org/gems/rbs-inline