Something was created by a creator. Now what? Where did purpose come from?
George MacDonald was quoted as saying something to the effect of: "did it ever occur to you that God created you for one purpose: simply to love you". All the stuff that we do would then flow from experiencing that reality. This would suggest a view of us as God's children (indeed, in Gen 1, the point is arguably that in the end, God reproduces after his kind [as much as is possible]). I don't have kids, so I don't no, but it seems like that is ideally why people have children--to love them.
The Westminster Catechism is related: "What is the chief end [purpose] of Man? The chief end of Man is to glorify God and to enjoy him forever." It is less satisfying, since it seems to sound like it requires toil on our part, although I doubt the authors saw it that way.
Why is the rock there, in that particular location? Well, we know why, it's because it fell from the cliff above, which was sundered by the earthquake, which was caused by the tectonic plate movement.
So we have a reason why the rock is there. Does that mean the rock has a purpose? No? But that's why it's there though!
What if I deliberately picked up a rock and placed it on that location instead. Does it have a purpose now? Does my hands have that power?
The idea that a creator imbues their creation with purpose by creating them is just as arbitrary as an earthquake. It's wordplay at best, where the layman's "purpose" is being confused with a sort of higher cosmic meaning "purpose". The purpose of a hammer is to drive down nails, but that doesn't mean the hammer has a purpose in the way we are talking about here. But that's exactly the mixup you do when you say that the creator gives the creation it's purpose. It's kinda funny because it elevates hammers making them fulfilled and meaningful, but rocks are left to suffer in their nihilism.
> The purpose comes from why the creator created it.
Some higher being might impulsively created the universe out of boredom, in which case there would be no ultimate purpose at all. But maybe they created it intentionally, with a purpose, which is the ultimate purpose of universe and everything inside it.
So no, it's not what you condescendingly said "wordplay at best." There can be a relationship between the purpose of a creation and the reason why the creator created it. In fact, for many everyday things, the purpose of their existence is exactly the reason why the inventors created them.
(I'm not arguing that there exists a creator of the universe. I'm just showing how irrelevant, to put it mildly, your seemingly strong argument is to the post you replied to.)
How about this angle: Does that creator itself have any purpose or meaning? If God exists, is he utterly nihilistic and void of meaning? After all, there was no creator to give God purpose.
If God does have purpose somehow, that shows that purpose does not only come from being created. Problem solved.
If God does not have purpose, then that creates a rather strange situation where a being without purpose can create beings with purpose. Presumably we too can create things with purpose, in a godless universe, and thus infuse the world with purpose ourselves.
Personally, I think people are too quick to mix up purpose (the how) with meaning (the why). There are all kinds of mechanical reasons as to how you came about, from nature, your parents, circumstances. And some of those reasons even include agency, for example, your parents might have decided to have a child. That's a decision they took, not just random luck.
But these are reasons as to how you came about to exist, not the actual meaning behind your existence. Meaning is something else entirely, it's a very difficult topic to struggle with. But we diminish it greatly by dumbing it down to "the meaning with your life is whatever intentions behind what created you". Our lives does not belong to our parents, nature or our creator, but rather, ourselves. And thus it's only we who can imbue that life with meaning, nobody else.
Likewise if God made me to, say, love and forgive others, I can either serve my purpose or not. But the purpose is given to me by the intent of the creator.
Imagine your father always wanted a child, and for the child to take over the family business. Is your life without merit, utterly void of value, if you become a fireman instead? After all, you are not fulfilling the purpose, the intent, of those who created you. Anything outside their specifications is meaningless nihilism, right?
Personally, I think there is more to "purpose" than this definition, it's a very small definition that does not truly compass what people mean when they talk about purpose.