Cards are cool! They act as entirely different areas for objects and logic, like all new screens of stuff!
The Top Card is the one that always appears first; first when you play, the first that loads in, and the first thumbnail you see.
I like using Top Cards as cover art like game cases- so I'd set one up by giving a piece of art some logic that says.
When this is created >
Send player to card [ ]
That way you open up the game and it jumps right in!
I love your art btw!