It is all relative, Andy. What is slow for one person is gut-busting, road-scorchingly fast for another.
When I break 25min for 5km, I'll be pleased with myself.
Getting older has a significant impact as well. 1984 was over 30 years ago . . .
Once over 50, it starts to drop dramatically.
This summer was going to be my racing year. I'd worked hard on technique. Worked on strength. Pushing stamina over winter. I just needed to put it together with speed work. Goal was to get a place in a division 5 race, maybe get promoted to div 4.
Covid hit and I've lost a racing season. I'm in my mid 50s and every year lose some aerobic capacity. It is almost impossible to overcome that, I was racer of indifferent ability anyway.
So don't be harsh on yourself. Don't expect to be as fast as your (much) younger self. Get out and enjoy being able to run. Look at mixing up road running with exploring some trails and wild places.