If each cell has multiple mutations, why do most of us have normally-functioning tissues and organs?

Most of us has normally-functioning tissue and organs even if the cell has multiple mutations because of DNA repair mechanism. This repair mechanism has multiple processes by which any damage in the genetic material can be repaired before the protein is synthesized. In human beings there are many factors like environmental factors and metabolic activities that can cause mutation in DNA but the repair system does not allows the abnormal DNA to form abnormal proteins this saves the abnormal functioning of tissues and organs. More than 1 million molecular lesions per cell are repaired, these lesions leads to structural damage and the damaged cells are killed by apoptosis. This repair system continues as the cells divide and any alteration in the DNA is solved prior to the protein synthesis this result sin normal functioning of tissues and organs.