How to build a simple content approval workflow between an administrator and a user? I have the following requirement on a Drupal site.

User interface (Authenticated user):


A simple form with some text fields
Radio buttons to select the content type
A submit button to submit the form


An authenticated user has to submit a form which will have few text fields and a content type selection.

User interface (Administrator):


A grid to see all the submissions.
A column with two buttons beside every submission "Review" and "Send back".


Once submitted the form, admin will be able to the submission, they may either review the content or send back the content to the user.

When clicked on review button, the page has to take to "Add content" page with title, description, attachment and other fields pre-filled.

When sent back, user will be notified and they may review the content and resubmit the form.

I achieved this requirement using Webform module which captures the user submission and written a custom module to fetch the webform submission content and creates a node based on the submission. I have yet to work on the "sent back to the user" part.

I'm wondering, if there is any simple way of doing this workflow.

P.S: I have already tried Workbench but I'm looking for a simple workflow where a non-technical guy (administrator) could easily get it.
Have a look at my answer to "How to implement a multi step approval with webforms/entityforms based on form components?". It explains how you can implement a workflow that is pretty (though not exactly) similar to what you are looking for.

To do so, it "only" requires you to use these modules (and regular content types):


Rules.
Node Convert.
Flag.
Content Access.


Use such approach, it does not require modules like "Webform" or "Workbench".