But isn't "serverless" fundamentally a restart-the-world model, which would make it more like CGI than FastCGI which is a application server type model which isn't fundamentally that different to putting a reverse proxy in front of a HTTP speaking application server?
No. In AWS Lambda at least, the container your application runs in lives through multiple requests until some period of inactivity passes and it is shut down. It isn’t “running” in the sense that your code is in control, but long-lived things like database connections do not need to be re-established on every request.
