I don't think that there exists a list of essential packages for the public.

What parts are considered essential depends on whether you need ADRIANE. I think that is safe to remove the Libre Office packages. Removing or upgrading packages might include the removal of ADRIANE.

I think that you should create a list of all packages first. The dpkg command can create such a list.

If you find a file and want to find out to what package it belongs to you can use the search function of the dpkg command. Then you can try to remove that package by using the apt-get command with the --simulate option. This will show you what other packages would also be removed.

As you can imagine it will be a really time consuming task.