>> Slackware Linux is the oldest surviving Linux distribution.
>Debatable. Slackware and Debian were started in the same year, though the far-more-ambitious Debian project took much longer to reach its first feature-complete release.
It is always interesting to see how history rewrites itself. Slackware was passed around as a beta in April of 1993 and by the time the Debian Manifesto was published in August, Slackware had hit version 1.00 a month before, the Slackware repository was hosted at ftp.cdrom.com, and SLS was quickly fading away. I believe what killed SLS was failing to release often in the early days (months were forever then), and fooling with the kernel far too much. One of the last SLS releases (after Slackware 1.00) shipped with a kernel that had been modified to add the concept of kernel modules and modularized most of the major drivers. Of course, it was completely broken and unsuitable for production use, but it was a concept way ahead of its time.
Back to Debian. Ian and I spoke on the phone at length around the time of the manifesto. He had wanted me to give up Slackware and join Debian Project, and was going to give me a vote in the development (like anyone else who wanted to join). I am not going to claim that Debian is a Slackware fork, but in August of 1993 that's pretty much what Ian had on his computer. I'm not sure that I actually saw a copy of Debian proper until around 1995.
On the oldest distribution topic, didn't H.J. Lu distribute two floppy disk images (a boot disk, and a root disk) before MCC+?