There are no clear updates, except some vague bug fixes and performance improvements
Amazon provides its Kindle Fire (1st Generation) users with a 6.3.2 firmware version, even though no clear updates between the 6.3.1 and this one are specified. So if your tablet didn’t get this software version, follow the steps below to update your Kindle.Therefore, first make sure that the battery is fully charged (or at least 40% charged) and then connect the device to the computer through a USB cable. Copy the downloadable file to the root folder of the tablet’s storage (do not copy to another folder on the device, otherwise the update process cannot be started).
After the file is successfully copied, disconnect the device via a safety remove feature provided by the computer and go to Home → Quick Settings → More → Device → Update Your Kindle.
During the update process, the Kindle will restart twice and, after the first one, the Kindle Fire logo will be visible on the screen.
After the device has restarted for the second time, and of course the upgrade process is a success, the system version read should be 6.3.2.
Now, follow the link below and download the latest firmware for your Kindle.
Amazon Kindle Fire (1st Generation) Firmware 6.3.2