While I was looking at this, it struck me that life expectancy is irrelevant unless it is taken into context, the individuals that are setting the life expectancy data were conceived, born and hit puberty before WWII and this is the time that the foundations for their future health was set. There is plenty of information out there indicating that this process starts at conception and generational health is passed down through maternal nutrition, one example being Okinawan centarians outliving their children and in some cases grandchildren.
As for the other cultures you mentioned, I don't think any of them knew what wheat was.
Diet plays a significant role in health, but there are a lot of other factors that also play key roles.
Inuit & Massai were virtually 100% animal foods, can't name them, but there were others that were 95% plant foods, mind you it was likely that this was not by choice, more likely like the Hunza, a case of scarcity, some ate grains others didn't, and theres an entire spectrum of diets between these, so with all the information available to you, take the best guess of what will be best for you.
Our bodies have multiple back up systems that overlap in their duties, when one system is overloaded, other systems step in and shoulder the load, most of the time you will not be aware that anything is wrong, because these are only supposed to be temporary failures, if this condition is maintained for an extended period, eventually you experience the failure as expressed by a chronic health problem, when this happens all the walls come down.
Most people are surprised when they are suddenly confronted with this, but it's not sudden at all, it can take 20, 30 or even 40 years of abuse, can a doctor cure you in a month or year, no, it may well take 10, 20 or 30 years of care to rebuild your health or it may not ever recover.
So if you read all the information available to you and think wheat & gluten is safe for you and you have no ill effects from eating it, then put your money on the table, eat the bread and pasta and see if your bet yields a positive or negative return.