Good question. NFT - N) Non, F) Fungible, T) Token. ;-)
But to the fungible question. The definition of fungible uses the word "can" in some texts. So, yes. They are fungible because they "can" be traded for other assets of equal value.
And to your point, there is no volume. This is because of the limited audience. The NFTs, the baboon motif, are targeted at toward people easily swayed, 'children' if you will. So, 20-somethings with absolutely no financial experience, knowledge.