Numbering the content list in drupal (as simple as it sound) - possible via the UI? Went through the conf and the Drupalsite > Content page but couldn't find any where to number the list (or at least to get a nubmer of all contents of all entities and types - including Views, Panels, Webforms, ETC).

Would thank you for showing a simple way for numbering this list \ get a content-total number.

Here is the picture of my natural display of the content page... Thanks, Ben.
Looks like you might be looking for number of nodes by content type (among other things). If that's the case then you may want to consider the Charts module. It comes with a sample view that gives you both a tabular overview and a chart of these numbers.

The (accepted) answer to the question Views and node count for taxonomy terms contains another (views) based example.

The question Count of nodes by type contains some code snippets that may help to write your custom module to calculate these counts.

If you don't want to install/enable the Charts module permanently, you may want to temporarely enable it to (eg) look at the view for the tabular format display, and then create a clone of that view to perfectly fit your needs (and then uninstall the Charts module again). Of course the "Views" module is yet another module. But it's rare to find a site that does not use the views module, so that's maybe an acceptable compromise to consider (you might have Views available already)?