You can use RarePepeWallet.com to setup your own wallet and see all the cards. You can also check out what other people have in their wallet.
PEPECASH and the RARE PEPE cards are counterparty assets backed by the Bitcoin Blockchain. This is what allows them to not be copied and keeps them rare. Say a Rare Pepe card has an issuance of 100 total cards created. That number will never be increased. If 100 people each own 1 of those cards, another person can't obtain the card without one of the 100 current holders selling it. Each card is associated to a token that is traded between people.
Yes, I guess you can just go copy the .jpg image and save it to your computer, but it's not the same thing. That is a very childish thought. That's like saying I can go print a copy of the Mona Lisa on a piece of canvas and say that I own the Mona Lisa... it's not real or authentic, it's just a fake copy that's not worth anything and can be proven to be fake. The token/asset behind the card/art is what gives it it's value and authenticity. If you hold the asset, then you hold the value.
Ownership might be needed for playing a pepe game, although doing a game on a blockchain would be really slow, but for digital products you own it if you have a copy on your hard drive. There's only one Mona Lisa oil painting, and it can't be copied exactly, but for digital files they can be. The pepe images are fantastic, but I don't have to own them to have a perfect copy. Enforcing digital scarcity is impossible, so unless havng the blockchain pepe asset has value itself, the pepe images are essentially free, like movies and music on a torrent site.
Who owns the copyright on the pepe images, the card creator, or the card owners? Copyright is enforceable, just difficult to police for personal use.