All money, including bitcoin, ripple, dollars and even gold, are based on debt. Holding gold means (more or less) that you have done something worth that gold's value, and you hope that in the future you'll be able to exchange that gold for something of similar value. Dollars and ripple are the same, with a couple of subtle differences. In dollars, certain players can create new debt (new dollars) at will, limited only by the willingness of people to accept them. When you get a bank loan (or a credit card or whatever) that bank has created new dollars out of thin air by magic, limited only by their assessment of your ability to repay. In ripple, everyone is a bank, and everyone can create money through magic, just by finding someone willing to accept it.
Gold and bitcoin, though based on debt/hope just dollars and ripple, have the advantage that no one can conjure them at will. Gold and bitcoin are both past-looking, where holding gold or bitcoin is prima facie evidence that a party has already in the past done something of value for society. Dollars and ripple are more forward looking, where one party has received something of value, and the other party is hoping that they will do something of similar value in the future to redeem that particular debt.
#1 you are correct that all money represents debt. as you stated correctly money is used to split a barter transaction into two parts, and before completing the two parts of the barter transaction you have money on your hands which represents value but is not value itself.
this is in fact the point which many people on this forum get it wrong when they talk about "commodity" based money such as gold or oil. there is a difference between oil and gold in that oil is something you use and gold is mostly representing value but has almost no value on it's own. ok gold is very good electricity conductor and so forth, but it's price is high mostly due to speculation not it's intrinsic value.
#2 your distinction between forward/backward money is irelevant. whatever is used as money: sea shells, stones, gold, tokens, electronic transaction account money, etc., is as good as anything else as long as it is accepted in places where you wan't to spend it.
but... and this is important
#3 you stated correctly that two parts of the barter transaction may be split in time, which means that the money will be in your possession for some time, possibly long time and in this case money serves as a store of value for this time period.
some forms of money are better at storing value than others. if no one can inflate money supply by arbitrarily creating more money than this certainly helps preserving the value. gold and bitcoin fall into this category.
but... and this is most important
#4 money supply issue is just one half of the problem when money is used as store of value. the other half is commodity supply. if commodity is scarce then it's price denominated in money will rise. oil prices will rise for example as we consume more oil than we can produce etc.
so regardless of what type of money one uses to store value it will not protect you against future price increase of scarce commodities.
most people just assume other people will produce commodities in the future in sufficient quantities so that the only problem they need to solve when attempting to store value for future consumption is assuring no one can inflate the money supply. hence they buy gold or bitcoin.
but the real problem imho taking into account that supply of commodities especially food and energy can fall short of demand hence the price increase even in non inflationary money.
this is why so called "doomsday prepers" store food rather than gold.
