It's not serverless if you use Amazon; it's just that you're using Amazon's servers. There is hardware, and there is the signal, and then there is a chain of software between the two. That is all there is in computing, and all there ever will be.
You just deploy your code, and Amazon automagically handles scaling, etc.
Heroku is fine for that, but they spin your instances down, so the first request may well time out.