But deposit accounts aren't necessary for bank to create credit. Savers aren't required for capital
This is a lie.
Savings are required for investment, because currency is a representation of labor an individual has expended without yet receiving a payout from this labor.
For example, if I grow apples in my back yard and sell you the apples, you give me currency, which represents the amount of work, capital, and risk I put into growing those apples.
You can print currency without anybody working, sure. But then somebody has to work to build the capital that you're basically borrowing from him in this scenario. (The currency you just printed representing your debt to him). If the person wanted consumption immediately upon receiving your currency (i.e, he wasn't a saver) he would give it back to you in return for some service of your own, destroying the currency in the process (the currency found its way back to the issuer). In this scenario, you are now the saver, because you now have put in labor to pay off your debt to the person you originally paid, without receiving any immediate consumption in return (you just get the thing you "invested" in). I suppose you could have refused to accept your own currency, in which case I suppose one can argue there was no saving, merely the unfulfilled promise of saving, i.e, theft.
Long story short, unless somebody somewhere is willing to take on the disutility of working without an immediate consumption payoff (i.e, saving) then there can never be any investment.
Now it might SEEM like there might be capital created without savings if the fed were to right now print $100M, lend it to a bank, who lends it to a company, who uses it to finance building a better oil rig for example, but indeed the savers are those that accepted the newly printed $100M as payment for their labour. If this currency never is repaid by the issuer, then that's equivalent of the theft explained in the prior example.