That's how I started using Linux
big book with CD, I think it was "RedHat Linux Secrets 5.4" or something. 2.0 or 2.2 kernel.
Honestly, it was fantastic. And almost all of it is still relevant today. (Some of the stuff on xfree86 and the chap/pap stuff not so much.)
But it gave a really solid (IMHO) intro to a Linux/*NIX system, a solid overview of coreutils, etc. And while LILO has been long replaced, and afaik /sys
didn't exist at the time, it formed a good foundation.
I'll refrain from commenting on any init system changes that have taken place since then.
At 28 years old, it's safe to say Leo doesn't use KDE.
Happy birthday!