Technically my first race was a Turkey Trot with my sister who I think was training for a marathon. Second race was a Memorial Day 5k this year. I ran it as a training run until I got near the end and I realized there was someone in my age group pushing a double stroller right behind me so I knew I couldn't let him pass me right at the end. That would be embarrassing.
There was also like a five year old girl who had been ahead of me the whole race so I had to keep up my pace once I saw her slow down with like a quarter mile left...couldn't handle that potential embarrassment either lol
And then right at the very end I saw someone in my age group just ahead of me so right when I felt like I couldn't keep up my pace any longer, I was forced to speed up to pass him.
The race was cut short because a business along the route had caught fire that morning so it ended up being pretty much 4k on the nose, maybe 25m short. I finished in 21:35 so I wasn't particularly fast but I was proud of myself for having the will to keep going at the end. Got second in my age group (...excluding the overall event winner...) so I got this really tiny dog tag with a label maker label on it as my trophy. I thought it was really funny and fitting for my middling performance in a small, local "race."
My first race where I'm going to actually try to do well will be a trail run Saturday morning through a mountain bike park going over some of the bike obstacles so it looks like it should be quite fun.
You could maybe just start running around their fence until they come out to see what is going on.