The explanation sounds complicated to me even though there are no technical terms in it. I'm not saying your analogy is bad but it could use some fine-turning here and there. For me, I just see bitcoin as Money but in a digital system without any mediator or intermediary to dictate or monitor if it could be spent or how it was spent.
btc IS the cup all assets gold btc and other crypto are the cups where the money the water flowing in..
Gold is not decentralized so it would be wrong to fit both BTC and gold in the same category.