I would like to echo the words of Mojo31. I'm 62 been riding 2 years after many years off and I also considered myself active. My first ride two years ago was on the street I live on, it's to be fair quite hilly. I rode 3/4 of a mile and turned around to enjoy the "downhill" finish so my first ride was 1.5 miles and to be honest I thought I was going to expire before I got off my bike.
But something made me stay with it. At first I might ride once a week and winter I wouldn't ride at all. All during the winter of 2018-2019 I was planning, setting goals and fixing up my bike. When spring 2019 arrived I was anxious to get outside. That Spring/Summer/Fall of 2019 I estimate that I rode no more than 700 miles. But it was enough to get me thinking about riding bikes so I continued working an a trainer all last winter.
So now I'm in I think fairly reasonable shape and have reasonable bicycle chops. I ride between 100-150 miles/week sometimes more. On Saturday I did a 53 mile ride on a rail trail using a hybrid with street tires. I main concern for the ride was keeping my cadence numbers over 80 rpm, striving for 95 rpm. Let me say that the trail I was on was absolutely packed with cyclists. In the almost 4 hours I don't think I was passed by another cyclists but I passed many. My average speed according to my Garmin was 13.7 MPH. So two years ago I rode 1.5 miles and nearly died, today I do 50-75 mile rides. I average about 17-18 mph on 30-40 mile road bike rides with moderate climbs and maybe a serious climb or two.
So OP Cooper1991, you average 8.7 MPH, I really don't think that is bad at all given that you are just starting out. It takes time and effort and quite a few visits to the hurt locker. I would say that since you took the time to post this information on a forum that you want to do better and I hope you do work at it. I did a 35 mile organized ride at about the 5 month point into this foray. The route has hilly I think about 2200 feet but I had to get off 3 times and walk. I was a bit humiliated but it served the purpose to light a fire under my backside and today I would do that same ride without even stopping. Assuming that you are in a region that is looking at winter shortly I would urge you to find a way to keep working at your fitness with the goal of doing the same ride you just did at an average speed 25% faster 10.5 MPH, do it man!