I'm 65, still train diligently, and would be touch and go to beat 19:23. I think it's attitude rather than speed. I would call myself a competitive athlete as I train with the goal of racing others in my age group, and competing in Masters Championships.
Someone who is running for a local club or team and competing to try and win a small race, or place well, and who is running 16:30 is a competitive athlete, just not a particularly fast one.
A hobbyjogger is someone who runs for the enjoyment of the activity alone, and is happy to be fit, enjoy the social side, and just complete the race.
Incidentally, there is no way the average person can run a 16:30 5k. That's 5:19 per mile. I doubt if you could take the average American male - age 20-40 years old, you could train much more than 10% of them to run one 5:19 mile, let alone 3.1 of them back to back.