A purpose doesn’t have to imply concious design, intent, or immutablity.
I am aware of the nature of natural selection and how it builds complexity over time through various selection pressures not all of which are constantly aligned with end result. And although wings were initially little nubs not "designed" for flying you could say that wings are they are now are "designed" for flying.
"Design" and "purpose" as I've said many times throughout this thread is a word that flows better. It is a linguistic choice and you are taking the argument in a direction thinking I don't understand some trivial point about natural selection.
To put it another way, the fact that the inputs (mutations) are random does not mean the outputs have no purpose.
If I said “the purpose of eyes is to see”, would you really disagree with that?
Also, it is entirely possible for body parts to have multiple purposes, that is quite common.
Not true. Natural selection can produce the same results as artificial selection. They are both effectively the same process where in one scenario the guiding hand is human and the other scenario nature is the guiding hand.
If both nature and artificial selection evolved a mechanism that is very specifically and efficiently able to do one thing and one thing only does it mean that the thing evolved has no purpose? No it doesn't.
Either way we're getting into a linguistic and philosophical argument on the meaning of the word "purpose." These are traps. Ultimately we begin arguing about the definition of an ambiguous word thinking that the argument is profound. It's like all those arguments about "What is life." Pointless, "life" is the word that is loaded and ambiguous; any debate of that nature is simply an argument about the intricacies of a vocabulary word.