Question

What is the evolution people having different diseases and some are insensitive to some diseases

Answer 1

The evolution of people having different diseases and some being insensitive to some diseases is simply explained by the natural selection process of evolution. People get mutations constantly, as mutations can change the function of a protein, hence people can get different diseases depending on the protein involved, some mutations lead them to a phenotype which makes them insensitive to a particular disease. Another example is of infectious disease, some people have developed strategies to avoid infection or have their defense mechanism more powerful, hence are insensitive for that pathogen.