I have many email addresses, one for each user, on a subdomain like so: username@upload.mywebsite.com
I'd like to receive all of these emails into one Inbox for me to use, e.g. combineduploads@mywebsite.com
I'm using AWS Workmail and Route 53. I'm not sure where to start. Maybe this can be done with DNS records?
This can be done using AWS SES and AWS Lambda where you can setup a SES rule to trigger a Lambda function to forward the mails received to a predefined email address.
For more details refer Forwarding Emails to your Inbox Using Amazon SES. You can launch the CloudFormation stack to automate the majority of the configurations.