But the salient fact is that while God may reveal different parts about Himself to people at different times in their lives, those parts that God reveals about Himself are always the same parts making up the unified whole of God which is consistent, specific and unchanging.
God does not contradict Himself. Hopefully, by God's grace alone, our understanding of Him grows every day. But what is true about God today is still true tomorrow and always.
C.S. Lewis is a mixed bag. I think he misses the mark with his fable. God is unchanging.
There is only one name under heaven by which men can be saved, Jesus Christ. God brings men to Christ along various out-croppings of the one path to Christ. Hopefully, we are brought to Him staying as close to that one, true path as possible.
Surely, just as waters boil up from a vast, full spring, so does an immense crowd of gods flow forth from the human mind, while each one, in wandering about with too much license, wrongly invents this or that about God himself. However, it is not necessary here to draw up a list of the superstitions with which the world has been entangled because there would be no end to it, and so without a word of them it is sufficiently clear from so many corruptions how horrible is the blindness of the human mind. I pass over the rude and untutored crowd. But among the philosophers who have tried with reason and learning to penetrate into heaven, how shameful is the diversity! As each was furnished with higher wit, graced with art and knowledge, so did he seem to camouflage his utterances; yet if you look more closely upon all these, you will find them all to be fleeting unreality’s. The Stoics thought themselves very clear when they said that one could elicit from all parts of nature various names for God, yet without on this account destroying the unity of God - as if, indeed, we were not already more than prone to vanity, without being drawn farther and more violently into error by the multiplicity of gods foisted upon us! Even mystic theology of the Egyptian shows all have sedulously brooded upon this so as not to appear to rave without reason And perchance even at first glance something that seemed probable would deceive the simple and careless; but no mortal ever contrived anything that did not basely corrupt religion." -- John Calvin, Institutes of the Christian Religion Book I, Chapter V, Section 12 "Hence arises that boundless filthy mire of error wherewith the whole earth was filled and covered. For each man’s mind is like a labyrinth, so it is no wonder that individual nations were drawn aside into various falsehoods; and not only this - but individual men, almost, had their own gods. For as rashness a single person has ever been found who did not fashion for himself an idol or specter in place of God.
LOL....I think that's (part of) Lewis's point....GOD does not change, regardless of the name by which mankind refers to HIM. HE is the source of all that is good, and all good that is carried out by mankind is ultimately in HIS service, and to HIS greater glory, even if that human individual isn't particularly cognizant of it at the time.