How are you defining longevity and metabolic health? Are there are randomized clinical trials that shows fasting is superior to other methods when calories are equated? I am not aware of any.

If you eat the exact same food and volume but only change the timing (fasting vs. throughout the day), you won't see different health outcomes. There are not studies tracking fasting long term to show it improves longevity. There is more data to support general caloric restriction (rodent models). Any form of caloric restriction improves insulin sensitivity.

And regarding our ancestors, we have no idea what there metabolic health was. We don't know if eating pattern, specific foods, or physical activity levels played larger roles. Ancestors is very general as well with many different lifestyles depending on geographic region.

Overall, when we look at the totality of the data, fasting isn't one of the best things you can do. If it helps someone maintain caloric load, then it can be very useful for them.