RStudio Installation on Mac OS X 10.15 is missing File toolbar (i.e., File, Edit, Code, View, Plot, etc.)

Joining you in laughing at human nature! (I hate it when this happens to me.)

Great. Please mark the solution for the benefit of those to follow. It's certain someone else will run across the same issue.

For future reference, please keep in mind the benefits reproducible example, called a reprex, even though not needed for your issue.

A couple of Mac specific pointers

  1. In the R gui (the alternative to RStudio), the history() command isn't implemented.
  2. To install.packages() from source that require compilation, you will need XCode installed from the app store and then enter in the terminal
$ xcode-select --install

You only need to do this once.
3. Failures to compile frequently happen due to a couple of causes.
4. The first is Mac's non-standard compiler tools. Very often Saint Simon Ubanek of the R Core Development Team provides a binary package with the problems fixed through deep magic. This may take a couple of weeks after updates to packages.
5. Another reason is missing object library dependencies.
6. brew is the best way to handle these.
7. If you use Anaconda, which is a great package manager and Python environment, don't use it for R.

Good luck, and come on back when you have other questions..