Those things matter, but you are falling prey to selection bias. I would suggest looking into tue children, siblings, and perhaps wives / mothers of those founding fathers to get the full picture. Your physical fitness and diet play a crucial role. But without modern medicine and specifically vaccines, we rely on the age old technique of have many children, the strong / lucky ones survive. When people desire a natural state, i think thats fine, so long as they appreciate it means literally more people you know die young, including some of your children. Thats how nature has always worked.