Why is it not possible to create electricity by forcibly putting electrons into the system and closing the loop?
What am I not taking into account here?


That is in effect what a voltage source does: It force electrons through a system if there is a closed loop.  

Or going to a more abstract layer: You need energy to force electrons through a system. In effect you are using energy to generate electrical energy. It all comes back to the law of conservation of energy.


  if we are able to put electrons into a system, close the loop so the electrons have no where to go, then the electrons would be constantly bouncing around together. 


What you describe is more like static electricity. We can pump a lot of electrons in an object and then isolate it. The electrons may move around a lot but that does not create energy.