Is TRUE enlightenment something that all beings other than Creator must strive for once created? Is Creator still striving for greater enlightenment?

It is very much the case that you are never done. This is true for us as well, for we are never done, and that is why we created you, to add something new to the party—a new set of possibilities, a new set of likelihoods in fact, and a new set of grand hopes for helping your galaxy overcome the growing liability from having spawned evil through the corruption caused by the fallen angelics reaching a true state of depravity, a selfishness that is total. When all one cares about is the self, there will be no limit on what one will do to others in wanting to take from them and give to the self. That is what has led to the depravity and the death toll throughout your galaxy of the predatory extraterrestrials who were corrupted, long before you, by dark spirits who worsened the disconnection from the divine already underway in those beings, thinking they were the ultimate expressions of existence and that they could really do anything. The truth of the matter is that no one can outdo God. You can resemble the Almighty, you can approach the Almighty, you can align with the Almighty and enlist the Almighty to add its energies to yours when you are wanting lofty things to happen, but you cannot outdo the Almighty. To set off on your own and leave God behind will condemn you to a lessening through your own choice to have only your own energies to work with, and not the ultimate source of power behind the entirety of creation. Having much greater power to work with is actually quite a thrill to experience. The fact it will only be in evidence when one is doing benevolent acts of loving kindness is far from being a penalty, but rather a blessing that will raise up the doer to exalted heights of greatness and joy that can truly be indescribable in their magnificent intensity. You are just scratching the surface of things with your physical existence and its limited array of experiences; there are far, far greater things awaiting you as you progress further—that will require your will, your decision to engage and stay engaged, and along with that, belief in the divine purpose and existence, for the greater good of all.