The bucket monster-market-jughj8 already holds the site. Try the website URL first. The -o /dev/null throws the body away and -w "%{http_code}\n" prints only the status code, which is all you want to know right now:

curl -s -o /dev/null -w "%{http_code}\n" http://monster-market-jughj8.s3-website-us-east-1.amazonaws.com/
aws s3api get-public-access-block --bucket monster-market-jughj8

A policy file is waiting in ~/policy.json; read it before you use it. Then lift the block, attach the policy, turn on hosting with index.html and error.html, and curl the page again.