There's a discrepancy between your job as defined in your playbook and your output as listed from crontab -l. I suspect that's just transcription but worth double-checking? (Walter and Dick have also spotted that.)
I'd also check that the ec2-user which is who you're creating the crontab as has appropriate permissions and ownership of /home/jwelby/ and can descend into that tree and "do stuff".
And finally, check your logs/journal. As Dick mentioned, the cron execution environment is restrictive, so it's likely whatever's happening will be logged under _COMM = crontab or UNIT crontab.service.
I'd get it working with a simple debug job firing every 5 minutes with a playbook which just runs a debug or touches a file, check for its execution successfully in the journal logs then increase the complexity in stages.