Hi there!
I may need a little more information to be able to help you. PayPal express checkout directs the customer to PayPal’s hosted payment area. Are you saying that the credit card/debit card option isn’t available when your customers see that area?
If so, have you tried testing this while using a default theme like Twenty Seventeen or Storefront? What happens when you switch your theme?
You may also want to try deactivating all plugins except WooCommerce and the paypal express checkout extension and see if it works.
Let us know what happens when you try that and we can help you with the next steps.