Currently Cardano runs as federated system, all current nodes (aka pools) where in control of IOHK (maybe also Emurgo and the CF, but I’m not sure about that)
There are several papers for all the different Ouroboros “flavours” and they are all basically proof of stake, but of course you are right: at the moment you can not stake your ADA. Best way to think of it is that everything is defined static.
It’s probably the accumulated given coins out of the chain to holders from the master node (nodes?) themselves. After releasing the coins you can only track what you gave and not what is where anymore.
If you didn’t get yet that Cardano is in federated state currently and staking would be live when Shelley is released, maybe and just maybe Cardno isn’t for you!
But at least, at this stage of the project, you own some ADA whisch make you somehow a visionary