There is a very basic principle of any sort of hierarchical arrangement that you are violating, whether we are talking biological evolution or textual criticism. Yes, any text or any biological organism takes 'ideas' from earlier ancestors. But when we are discussing what descended from what, and trying to decide what is the nearest ancestor of something - that is, what did that piece of text or organism evolve from - you look for features that are found in the parent but not in the grand-parent (or other remote ancestor). If the thing in question lacks the attributes of the parent, but has the traits of the 'grandparent', then they are siblings which share the same origin. But if something has traits unique the parent, then it is evolved from that parent and not from the grand-parent.
Even where it true that Tolkien got the giant eagle from roc of the Arabian Nights, and I don't concede that either, it would not be true that the Giant Eagle entry in the monster manual comes from the roc. Without Tolkien either the giant eagle entry in the Monster Manual would not exist, and we would only have the 'Roc' entry that closely accords with the bird of the Arabian Nights (a fierce giant predator that carries away elephants) or else we would have a giant eagle entry that almost certainly would lack the features of a giant eagle that are specific to Tolkien. Since the giant eagle entry has features that are specific to Tolkien's eagles, we can say with great confidence that the giant eagle entry is owed to the work of Tolkien.
Once you accept that principle, we can start looking at which claims about what in D&D comes from Tolkien are strong and which ones (like magic swords having names) are weak. But until you accept that principle, this conversation is pointless, as you are not equipped to engage in textual criticism at all.