Where I live (in Sri Lanka) Amazon doesn't operate, so eCommerce has been able to evolve in weird ways. We have closed WhatsApp groups where people buy products, or bakers using Google Forms to take orders. Small businesses use the internet without becoming 'internet businesses' themselves. And thus the market is actually more free.
This sort of commerce existed before Amazon, exists around Amazon, and will be around when it's gone. It's just people buying and selling things using technology, just a bit slower because human beings are allowed to pee.
An Actual Marketplace
In Sri Lanka small businesses use the Internet like they would use a phone number, or a catalog. It's a place for people to reach them or browse their wares, but it's not like they have an engineering department. Small shops are able to use technology, it doesn't use them.
For example, our baker takes orders through a Google Form and delivers twice a week. We pay cash. He pays no commission and doesn't go through anyone else. Clothing shops will take orders over instant messaging, and payment through bank transfer or cash. Some people have websites, but they're usually quite basic (but diverse). You get an ecosystem instead of one system. Global eCommerce is based on an expensive, complicated middle-man making things faster, but if customers are willing to wait you don't need a middle-man at all.