TryHackMe is another fun resource that gamifies cybersecurity. Through small challenges and lessons you can learn important topics without having to commit an exorbitant amount of time.
I just started using this (as you'll be able to see from my profile) but I really like it! It's definitely a great resource if you have a few minutes to kill and want to get a quick challenge in or even if you have a lot of time and want to tackle multiple things. There's a free version if you VPN into the lab or there's a fairly cheap paid version that gives you a Kali instance already in the network that you can get into from your browser. As I complete rooms/challenges I will most likely do write-ups on the ones I really liked or found very helpful and I will make those sub-pages of this page.