Currently we are working with 2007 document libraries and we are going to update the version 2016. We have only document libraries here no web parts and all. How to do migration to SharePoint 2016 without 2010 and 2013.
Try ShareGate Migration only tool. They have 15 days free trial. I have used this tool for SharePoint 2007 to SharePoint 2013 and pretty awesome and easy to use. I dont see any big difference between SP 2013 and SP2016 in terms of document library.
If its just document libraries you can use SharePoint 2007 web services to fetch the document library metadata, content etc and integrate with client side script to copy in 2016 environment.. Metalogix and other third party tool , i am not sure if they have upgraded their version for 2016 migration.
The fastest way is to use the "Open in Explorer" feature in the document libraries in the ribbon both in 2007 and 2016. Copy the files from 2007 source to 2016 destination and you're done.
This is true if you don't need author or version information to remain the same. Author will be the one who copies the files, and version will be set to 0.1 (if versioning is enabled) or 1.0 (if disabled) and checked-out (if check-out is enabled).
Otherwise a tool is recommended, and don't forget to set the content databases in read-only mode before you copy the documents. Users will quickly learn the new URL when you set the content database in read-only :)