The amount of DNA you have is much greater than that accounted for by your genes. Even with 50,000 proteins and a daily production rate of billions of protein molecules, the vast majority of your DNA is not involved in protein coding. Introns get clipped out before protein synthesis starts. Mutations in non-coding regions usually do nothing to the phenotype of the individual. Within the coding regions of alleles, some types of mutations have no effect on the resulting proteins.
Mutations do much more than cause genetic disorders or cancers.
They do not occur only in humans. Mutations are a way to introduce new alleles into a population. This means, mutations increase the genetic variability of a population. Genetic variability is essential to the process of evolution and the formation of new species. Without mutations in the genetic material of some earlier primate species, we would not be here.