I don’t know that people were created disease free...so no, it’s still why.
The issue is then about what you don’t know.....and of course what you believe possible or not to believe of what you do know....
If I wanted to know certain things in a given field I would inquire of those familiar in that field. The field you are talking about is the field of religion or lack of...not medicine. Therefore you might inquire of a Pastor or clergy...or go to their source which is God himself and the scripture (letters) He wrote. You don’t have to believe something to inquire of it. I don’t believe in fiction yet I enjoy good movies now and then...
Just so you know it’s rather interesting to consider the one book which claims to have answeres is the least book sought by those asking the most questions.