Truck not starting

I’ve tried jumpstarting and using a portable jumpstart to turn on my 2003 GMC Sierra 2500. When i turn the key to start, everything turns on, the dash, lights, radio and even the A/C except the engine. When i try to turn it on all I hear is one single click. I also notice that when i try to turn it on, the gas, temperature and battery gauges move except the oil, im not sure if that has anything to do but it is extra information. If i could get help or any advice before i send it off to the mechanic, that would be greatly appreciated, thank you