1997 Oldsmobile Cutlass car will not start

1997 Oldsmobile Cutlass Supreme mileage: 120,000 . This car is an International Series. This car will not start, I have replaced the spark plugs, checked the fuel pump, all of the basics! Compression test reveals low compression 0 to 70 psi in all six cylinders. I do not understand and I would like to know the possible cause! There is spark, it is firing but will not catch. Any help you can offer would be greatly appreciated. I am at a loss!