Debian 12 was released in June and has some newer, and some older, packages than Ubuntu 24.04. For example Ubuntu has LibreOffice 24.2.2 while Debian has 7.4.5.
Debian testing currently has a similar distribution to Ubuntu 24.10, though over the next 6 months it'll pull ahead of that, but Ubuntu 25.04 will likely have on average newer packages than Debian testing until its beta freeze.
Debian unstable has always had newer packages than the others.
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.
The RHEL 7 book from OP is most certainly still relevant. For example, my department at work has not managed to switch over to the brand new RHEL 8 machines just yet.
I started with a book too. But it was 1996, and the distro was Yggdrasil, and the book was a printout of all the man pages. I used it for a Prolog programming course, so that I didn't have to go to the university and use their computers. Of course, then I discovered the joys of different flavors of Prolog.
Conectiva for me. More than a mere printout of man pages though, it was actually translated documentation into Portuguese and a really useful intro book.
I was at a used bookshop the other day and found the same Caldera Open Linux 2.2 book and cd that I used to install my first linux distro on a pc. Man that was exciting!