There are plenty of good alternatives, but AWS is the 800-pound gorilla. You have to know at least a little bit about it in order to know why not to use it.
It's like saying you don't want to use React/Angular/Vue for your web app. There are good reasons not to, but at this point you should at least have some experience with web frameworks before making a technical decision not to use them. If your answer is "I don't know them and I don't want to learn them", that's fine for a personal project, but probably not a reason not to use them at your full-time startup. If your reason is "I know React, but for my specific use case, vanilla HTML/CSS/JS is better" then you are making a more informed decision.