Commerce Kickstart and product variations
TLDR: This is due to how Commerce Kickstart is configured for entering new products. You enter product variations while adding the product.

When you create a product in Commerce Kickstart, you're actually creating the node that the customer will see. Scrolling down the page, you'll see the ability to add the individual product variations (which are the actual product entities) like so:



This is an Inline Entity Form (aka IEF). See, normally when you'd use Drupal Commerce, you'd need to create all of your individual entities and then add them to a product using a product relationship field. But this a Drupal field widget take takes that step out by letting you enter in your product data and relate it to the display node in one step.

If you want to see all of the product variations, there should be a tab at the top of the Products admin page that will take you to a listing:



You can edit products here, but you can't add them directly because of how Kickstart controls the product add process.