What I've found is mainstream distros seem to have no respect for aging hardware. Especially if they're desktop-focused. I have had some success with Trisquel[0], netBSD, and FreeDOS. I'm confident I could get Gentoo working if I'm picky about ebuild selection and build everything on a more modern computer, but that does sort of feel like it defeats the purpose. Another option would be maybe to install a version of a mainstream distro from 2011, with the caveat that I'd only be able to install software included on the installation media. Debian Squeeze repos are long gone.
I feel like I shouldn't have to stray so far from the beaten path to do something on a computer from 2011 that I could do comfortably on a Packard Bell in 1992.
[0] On recommendation from an FSF employee. Hardware that can run free software top-to-bottom tends to skew a little older, so Trisquel needs to run well on older hardware.