Conveniently, there's a table of contents at the start that hints at the later topics:

  Different kinds of numbers
  Conversions and type inference
  Generics and enums
  Implementing traits
  Return position
  Dynamically-sized types
  Storing stuff in structs
  Lifetimes and ownership
  Slices and arrays
  Boxed trait objects
  Reading type signatures
  Closures
  Async stuff
  Async trait methods
  The Connect trait from hyper
  Higher-ranked trait bounds
  Afterword

So 17 sections, 16 technical (excluding the Afterword) and only the first two focus on the int/float stuff. So to answer your question:

> Maybe, the int type thing is an intro to some other thing?

No, it's not an intro, it's just the first two sections.