Disconnect the battery from the charger or jump source. Measure the battery voltage directly on the terminals.
It should be very close to 12.0 VDC - 12.5 VDC. If its less, the battery needs to be charged. The clicking tell me that the battery voltage is dropping below 8 VDC when you crank it. Thats NOT good! Probably reading more like 4-5 VDC.
Have someone attempt to START the Jeep while your measuring the battery voltage with the meter. If it drops below 10VDC whe you try to crank it, its TRASHED!
If the battery has caps on it, check the water level. If its low, top it off and then try to jump it. Remember,,, the battery has to build up a charge before you try to crank on it. Let it charge for 15-20 min and then try it again.