It is a common problem, that basic file properties like creation and last modified date and original author/last editor are lost during upload of files to SharePoint via Windows Explorer.
I read in a post about `SharePoint 2007' that the original creation and modified date are still stored in SharePoint and can be shown:
It's still kept with the document, it's just not where you'd expect it to be. When you open the document from the document library and view the metadata using the Document Information Panel, you'll get options to switch from: Doc Properties:Server (SharePoint), Doc Properties (Original Doc Properties), and Advanced Properties. Within the Advanced Properties, you'll be able to view the original creation date.
However I do not find a way to display those "Original Doc Properties" in my documents library in SharePoint 2013.
How can I do that`? Is it a question of content type or library settings?