2000 Ford Contour won't start unless jumped. New battery

Check the ground wires from battery to chassis/engine block

When you jump start a vehicle all you are doing is adding more voltage(power) to your battery and also giving you battery a seperate ground point (other vehicles grounds) if the starter is turning over the car good off 14 volts from another car running it should still turn the car over with a good battery putting out 12.5 volts @ crank. I would be checking your battery and earth points before changing starter or solonoid.. Use a voltmeter over battery terminals it should have 12+ volts to crank engine over. It is possible the starter is worn and needs replacing. This would give you a very sluggish cranking (turning over very slowly) if this is the case replace starter?

Happy holidays too you tooo

Happy motoring

Dave H