The low life expectancy in Egypt seems cherry picked from one search result you found? Seems to be about a single village with data from about a century?
Animal husbandry is the root cause of a host of common diseases.
And Egypt has always been surrounded by nomadic tribes. Leaving the kingdom must have been so much easier than leaving capitalism today.
Traveling by foot across the wilderness into a civilization you know nothing about - not the language nor the customs nor anyone eager to accept you as a foreign migrant?
A bit more than that.
https://en.wikipedia.org/wiki/Against_the_Grain:_A_Deep_History_of_the_Earliest_States
Animal husbandry is the root cause of a host of common diseases.
Traveling by foot across the wilderness into a civilization you know nothing about - not the language nor the customs nor anyone eager to accept you as a foreign migrant?
Trivial, really. They just used Egypt GPS.