Is it possible to use AWS and Arduino Uno to upload data from Arduino to a website running on my localhost?
No, it is not (easily) possible.

AWS has no access to your localhost - you are (most likely) behind a NAT router.

You could possibly open up port forwarding on your router and then ensure that AWS knows always what the IP address of your router is so it can connect (using some dynamic DNS service maybe).

However, that is not secure, and dynamic IP address assignments makes it a real pain. It opens up your computer to hacking from the internet.  A more secure method is to use AWS as the "central point" and have your computer go and fetch data from there rather than having it send data to your computer.