If you look at Ebay's rules regarding cancellation, you will see that buyers can request a cancellation and sellers can accept or refuse the request.
So, you hae no automatic right to cancel, especially if an order has been shipped.
All items show an estimated delivery date before you agree to buy - you have to read everything carefully.
There is no reason why Paypal would refund you unless the item fails to arrive by the latest estimated delivery date.
When the item arrives, you will be able to return it if you bought from a business seller but generally, returning items to China using a tracked service is just not worth it.
If you need your purchase sooner rather than later, you will have to buy another item from nearer to home and chalk this up to experience.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)