A searching question from Joshua:
Which then makes me wonder, would I sit and gaze at a living, naked young man for hours on end (without being forced to)? And if I would...then would that make that young man a work of art?
First I am glad that you enjoyed the statue of David on this abstract level as you describe. I suspect that you have yourself done some sculpting.
I have myself wondered how natural beauty is art,or not art. If I chanced upon a lovely scene of a small waterfall, ferns, smoothed rocks,an overhanging rowan tree, without knowing whether or not some gardener had created the scene artificially, I'd not know whether or not to call it art.However, my appreciation of the natural beauty is not without value, since I will be influencing others about natural beauty. I guess the same goes for a lovely human body. It's said by the faithful that God created lovely human bodies, in which case they are works of art, as is all of God's amazingly fantastic creation. Others believe that lovely human bodies are the products of determinism with no artifice involved, neither God's artifice nor man's artifice. I may say that I am one of the latter sort of believers.
I think your question goes further than this though. Your question also brings in the consciousness of the human participant in an experience, and asks whether or not the human participant, audience or gazer upon David, is an active agent in the status of the artifice as 'art'.
This is rather like the old metaphysical question 'if the tree falls in the forest and nobody hears it, does it make a sound?'I belive that this depends upon how one defines 'sound' and for the art audience, how one defines 'art'. As far as I'm concerned,since I don't believe that art exists in a vacuum, but is bound up in the life of a society, your participation increases the value of David as a work of art. Likewise your loving appreciation of the real living human body increases that body's value to the model or the lover, and whoever else is concerned.