Find references / go to definition / rename has absolutely nothing to do with types.

It absolutely does. Without static types an IDE/LSP can’t reliably find all the references / definition and therefore can’t refactor reliably either.

Consider something like this:

class Foo:
  bar: int

class Baz:
  bar: str

def a(f: Foo) -> int:
  return f.bar + 1

def b(f: Baz) -> str:
  return f.bar + "1"

Now imagine you want to rename Foo.bar or find all references to it. Impossible without the type annotations.