Go to Elementor > Settings > Post types > enable editor for Products and static blocks.
Products > select all demo products and move them to Trash https://gyazo.com/8b34bab62c87295af6174ba1643e8676 , then
> add new product > follow this article – https://woocommerce.com/document/managing-products/ > once you Publish your new product it will be visible in Products section and on Shop page. You can restore products from Trash, because they were moved gust to make the products section empty for you or you can delete demo products permanently.
About category, create a new one – https://gyazo.com/9a364192108b8f18492404df96d5c4f6 , then go to edit product > select category – https://prnt.sc/Dhlens6hxqQr
These things come from WooCommerce plugin, and are independent of the theme, so watch video tutorials of WC plugin.
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