Scientists have known for some time, of course, that active people tend also to be long-lived people. According to multiple past studies, regular exercise is strongly associated with greater longevity, even if the exercise amounts to only a few minutes a week.

In the context of this post the biggest benefit to LISS (Low Intensity Steady State) cardio is that it is the most effective way to stimulate neurogenesis, that regeneration of brain cells. (Journal of Physiology 1 April 2016)

In a study published in the European Heart Journal [1] today (Wednesday), researchers in Germany looked at the effects of three types of exercise – endurance training, high intensity interval training and resistance training – on the way cells in the human body age, and they found that endurance and high intensity training both slowed or even reversed cellular aging, but that resistance training did not. https://www.escardio.org/The-ESC/Press-Office/Press-releases/endurance-but-not-resistance-training-has-anti-aging-effects

https://www.health.harvard.edu/staying-healthy/harder-workout-intensity-may-not-increase-your-longevity

https://www.reddit.com/r/bodyweightfitness/comments/a7m5ct/i_wrote_this_guide_on_how_to_lower_your_fitness/

I haven't seen any mention of HIIT regarding people who live in Blue Zones, it just says 'Constant moderate physical activity – an inseparable part of life'