Isn't this something which you can do with Jenkins? Pull code from Github and deploy it on S3 bucket?

I learned Jenkins creating the pipeline to AWS in less than a day.

Yes, but here you don't need to manage a Jenkins installation.

Right. But in this system, I'll need to manage Netlify.

To be honest, there is nothing to manage in Netlify. Just first time connect the git repo during sign up procedure. Additional benefits (at least for starter) are 1 click SSL management. They also provide functions and form, but I have not used them so not aware of how useful they are. :)

Sure they are not a huge improvement compared to your setup. But streamlining the procedure for someone not familiar with the pipeline is a great benefit.