I run a retail home appliances and cookware store, I want to create an online platform/eCommerce store to expand my business. So can I use images from the manufacturer's website or from other eCommerce giants? This shouldn't be a problem because I'm only promoting their product and since I run a retail shop there shouldn't be any legal/copyright issues.
No. You cannot. Copyright and trademark law applies no matter what you are using it for or for whom.
But just ask for permission. This removes all ambiguity. Promoting their product that you are selling is in their best interests, too, so marketing may help you.
That said, some companies still want to protect how their product is presented and may not want you doing that if they feel you won't show it in the best light.
Many manufacturers offer media packages or licenses to their product pictures with specific terms. These can include special contracts, partner status, usage restrictions and so on.
Without expressive permission you would violate IPR rights in almost all juristications. (However the Risk might be low to actually be prosecuted, but that's nothing you want to build a business on)