You have two grounds in your vehicle, an engine ground and a chassis ground. There are one or more straps that connect the engine ground to the chassis ground so that both are at the same potential.
If you were connecting the negative jumper cable to a chassis ground and the the ground strap(s) were corroded/broken or otherwise not very conductive, you would have a high resistance in the loop that includes the starter and battery. This would reduce the voltage and current available to start your vehicle.
It should have started if your negative jumper cable was connected directly to the engine block or head. That is where the starter is grounded.