I've been hopping Linux distros since I decided (for reasons of my own) against intentionally using systemd-based distros. I'm not interested in systemd flame wars, so don't bother here.
Waaaaay back in the early-to-mid 1990s, my dad sent me a box of 3.5" floppies. On these floppies was Slackware Linux. I don't remember the version, but I think I have most of them kicking around still, so if I felt the need, I might dig them up and see if I can install enough to get a version number from it. What I do remember is that it had kernel version 0.99pl10 on it.
Since my introduction to Linux on Slackware, I've used Red Hat/Fedora/CentOS (professionally and personally), Debian/Devuan, Arch, and Aurora (a Red Hat derivative for use on the Sun SPARC platform), in no particular order.
It's interesting, having to find all the dependencies again and having to re-compile kernels to get something newer than what comes in the box.