Hello Amin,
Thanks for writing in!
WooCommerce uses two image sizes for your shop, the product catalog and the thumbnail size.
Your shop index and product archive pages will be using the thumbnail size. This is why your images were a lot smaller compared to the single product pages which is using the catalog size. To avoid your product images from getting cropped, please set the catalog and thumbnail sizes as big or greater that the uploaded dimension of the image. Please go to Appearance > Customize > WooCommerce > Product Images and set both the catalog and thumbnail to 900. When you upload a 725x500 image, it will no longer be cropped. And if you upload a 1200x800 image, it will be cropped.
To apply the new WooCommerce product image sizes to the previously uploaded images, please install Regenerate Thumbnails plugin to regenerate the WooCommerce image sizes.
We would love to know if this has worked for you. Thank you.