What was the first version of Ubuntu and where can I find it?

Ubuntu's version numbers are made using the year and month of their release date: Ubuntu 12.04 was released in April 2012, Ubuntu 11.10 on October 2011 and so on.

Ubuntu 4.10 was released in October 2004 and is the first Ubuntu release. As there wasn't any Ubuntu version released in 2001 there is no Ubuntu 1.x.

The image(s) are currently available here. It supported x86, powerpc and x86_64 - but of course this release is not currently supported!

Ubuntu Warty Warthog was indeed the first release by Canonical[1]. You can get its image from here.