It seems Alteryx does not have option to add metadata while adding the S3 object using S3 data connector. It has to be done using REST API calls via download tool or via javascript tool. As S3 is widely used now to store large files it would be handy to be add the functionality to add or extract metadata via S3 connectors.
It will also be useful if S3 connectors accept a field name in the object name instead of hardcoding the name or path.