This is the main thing keeping me from going back to Ruby. I don’t want to go back to the stone age where there’s no or poor static analysis
If you're looking for static analysis in general, please note that there are mature tools available. Rubocop¹ is probably the most popular and allows for linting and code formatting. Brakeman² is a vulnerability scanner for Rails. Sorbet³ is a static type checker.
The tooling is there if you want to try things out. But, if you want a statically typed language then that's a debate that's been going since the dawn of programming language design. I doubt it's going to get resolved in this thread.
¹ - https://github.com/rubocop/rubocop