We all rely in part on others to overcome our disabilities. Physically disabled people are more obviously dependent than others. It is our disabilities as well as our abilities that tie us to others on this earth. God has created a universe with a tremendous amount of diversity of living things. All things in the universe have a purpose, be it physical or spiritual, which gives it a life force.
All life forces are different and complex.
It is the diversity of living things that make the world. No two things on God's earth are exactly the same. What we view as normal varies from one person to another. Depending on where we live physically, emotionally, and spiritually we see things differently. God the Creator has allowed the diversity of the world to develop, and with it comes good, bad, health, and sickness.