You should better consult a lawyer than a bunch of random people if this is important for you. Or better yet: not work for a company that tries to make you sign such agreements. And especially not this one :) I don't know where you live. In my country (France) overly broad non compete are not enforceable, and also you need to be paid during the non compete period (at least 1/3 of your compensation or something like t…
I'm curious then what people do when they leave AWS. Do they just not work for 18 months?
Also, once again, do check the law where you live. It's very possible that non-compete only apply on stuff you worked on. For example, maybe if you did not work on S3 specifically, you might even be able to work on Google Cloud Storage if all you are considering are companies that make public clouds.