In the old jira I used to be able to select the paperclip button and it would dropdown attachments that were include in the individual jira case. We use this in our daily workflow to mention members and make sure they reference the correct version of the file.
In the new jira view I only have the link icon for websites OR I can re-attach from my local machine. This isn't a true use case since that would require the user to download the attachment from the main case description and re-attach it in the comment directly every time.