Just because the average age of life was 30 in those days doesn’t mean it’s impossible that a small number of people could have lived to be much older. Some did, poor or not. Heck, the average age in 1900 was what? 70? Yet I have relatives who lived to be nearly 100 years old at that time. And no, they weren’t rich, but just got by, like most people. Statistically, they didn’t exist then, even though they lived to be 99.
Your suppositions are not based on faith, but material fact. The trouble with material fact that is so old, is that lots of physical evidence has been lost over the thousands of years since the events occurred. It doesn’t mean those events didn’t happen just because we don’t have conclusive proof today.
Think about science. I read about it, but I have personally never conducted the experiments to prove all the scientific facts of this or that. I have to take what I read with a grain of faith, don’t I, because I haven’t personally seen the evidence with my own eyes. I am just going by what some scientist somewhere has published. Heck knows there has been fraud in the scientific world, because sometimes even scientists can make faulty assumptions, especially where egos are involved.