Mutations are mistakes.
“These mistakes are almost never helpful. Could you ever expect to improve an encyclopedia by adding more and more spelling mistakes every time one is printed? The evolutionary literature acknowledges this very clearly:
Even the simplest of living organisms are highly complex. Mutations—indiscriminate alterations of such complexity—are much more likely to be harmful than beneficial.5
In summary, the vast majority of mutations are deleterious. This is one of the most well-established principles of evolutionary genetics, supported by both molecular and quantitative-genetic data.6
One estimate is that damaging mutations outnumber helpful ones by a million to one.7 Even most of the ‘beneficial’ mutations turn out to break things rather than make things, e.g. wingless beetles on windswept islands.8”
This process called Genetic Entropy “means that the human species could only be several thousand years old; certainly not hundreds of thousands of years, or we would have already become extinct.”
Read more details here: https://creation.com/genetic-entropy-vs-evolution