react-production-deployment | Deploy your React app to production on Netlify , Vercel | Serverless library

Was able to find the solution in the following blog where as stated the heroku runs by default npm start command if the Procfile is missing or add in the Procfile the line web: npm start and as stated in the blog the start command in package.json runs serve -s build where the serve is a package to point the build folder where is located the bundle and the index.html file and now it already works well. Heroku should have a default option to point to a default folder.. but all attemps that had tried failed... so thanks for @Bernard Bado and his blog for pointing to the solution.