In the past, before people hearing clearly of what we call medicine, any important weakness of the body was seen as due to a sin against Creator (or God, if you like).
Naturally, we are all born with a COMMON weakness, ignorance. It is like a powerful computer that has no useful saved data and no programs installed on it yet.
Jesus came on a flesh to save me from this 'original sin'.
How?... He did it by giving me the 'light' of true knowledge so that I can live without having important questions about my life not answered logically.
For instance, while many scientific books could be found anywhere, most people on earth are happy without taking advantage of the knowledge they provide. The same applies on Jesus teachings... they are not suitable for all human beings (why?... This is another topic

)