I’ll try to help you as best as I can by answering your questions and doubts
Basically, your body has 2 main metabolisms it operates on when it does physical activity: aerobic and anaerobic.
Aerobic is when your body’s muscles are fueled mainly by your oxygen (burning more fats during the exercise), so your exercise can be prolonged. For example, marathon training’s goal is to maximize the aerobic capacity of the body and to push the limit of aerobic endurance. This brings us to what Zone 2 actually is, in simple terms it’s the limit of your aerobic work. So think of it as highest effort you can sustain while staying predominantly aerobic. In swimming (my main sport) we train this metabolism too, often doing threshold work that sits above Zone 2, to give you the idea. Zone 2 is when you can keep going without too much lactate accumulating in your muscles, and your breathing is fatigued but you can still keep going at the same pace for a longer time. This is why
Zone 2 and aerobic threshold are pretty subjective, so that’s why you might find contradictory pieces of information.
Here is another recent study that explains it pretty well.
Instead, anaerobic activity is when your body’s exercise is fueled by carbs and the energy stored in your muscles (burning more fats in the recovery), often going in oxygen debt during such activities. As a sprinter, I mainly train my anaerobic metabolism, to reach an higher top end speed/strength and how to maintain it the longest. So I train also HIIT (in my case max intensity sprints, in general HIIT’s goal is to improve cardiovascular and muscle performance in a short period of effort) and VO2 Max (to be able to pump more volume of oxygen in my system during my races for example).
Your workout plan seems good and pretty intense, but it also depends on what your goals are: improving performance in a certain discipline, more strength/hypertrophy, having a more aesthetically pleasing physique, and so on. You are hitting the three main Zones, if your goal is general health I’d say you are doing great, you could try new activities like
Blaze suggested so jumprope or rowing machine. If you are looking for max hypertrophy you could reduce overall cardio activity. My only suggestion is that you could integrate your VO2 and HIIT sessions in the same workout. To learn more there are a lot of papers, and some reliable sources like athletes, trainers, and researchers, some online, some in person, some in books or research papers.