Prior to High Sierra there was a Finder sidebar item called All My Files. This showed you a big list of all of your documents. This was replaced with the Recents list, which only shows documents you have opened and leaves out files you have created or downloaded, but haven't opened yet. You can easily re-create the All My Files list by making a Smart Folder and adding it to the Finder sidebar. You can customize this Smart Folder to better fit your needs.