Source: https://divibooster.com/add-an-add-to-cart-button-to-the-woo-products-module/

This adds an ‘Add to cart’ button to each product on the shop page.

// START Add 'add to cart' button in the shop loop.
// Source: <a href="https://divibooster.com/add-an-add-to-cart-button-to-the-woo-products-module/">https://divibooster.com/add-an-add-to-cart-button-to-the-woo-products-module/</a>
add_action('woocommerce_after_shop_loop_item_title',
'woocommerce_template_loop_add_to_cart', 41);
// END Add 'add to cart' button in the shop loop.
Code language: JavaScript (javascript)