Agreed with Arjun. For anyone still looking for a way to build a CI/CD pipeline for Serverless apps with CircleCI, here is a post - https://seed.run/blog/how-to-build-a-cicd-pipeline-for-serverless-apps-with-circleci

I'm one of the authors behind Serverless-Stack.com. It has step-by-step instructions with screenshots and code samples for creating a React.js single page CRUD app hosted on S3 and served out from CloudFront. Over 50 tutorials that take you all the way from creating your AWS account to setting up your app with your own domain. Here is the demo project from the tutorial.