For money to have a positive time-value it means that people prefer having any amount of money now over having the same amount of money later, all else equal. It is very hard to argue that this is not the case, because if you have the money now, you can have it later (by not spending it), but also you can spend it now, whereas if you don't have it now and only have it later, you have it later but you can't spend it now. Therefore having it now is always a better alternative, again, all else equal. Negative interest rates can be explained by other reasons that do not imply money having no time-value.
> if you have the money now, you can have it later (by not spending it)
I think this is where your argument breaks down. As pointed out by many other comments, there is non-zero cost and/or risk to ensuring that if you have money now, that you will still have it later. Matresses burn, stashes get stolen, vaults or insurance cost money. FDIC is limited.
