I am not a marathon runner.
But you still could be, unlike be an effective sprinter. Endurance training and longer distances are often what people prefer when they get older and it's just because how human body works.
The longest distance i'v ever ran is half marathon and it 1.35 but it was without any proper training, just some uphill interval drills + tennis/football, which obviously gave me some type of endurance, but i have to say, it was the most painful 1.35 i'v ever spent on my life so far considering i ran it with a guy, who had full marathon on his belt. Im more of a 400-800m runner, faster than 99.9% but still lacking some maximium speed for 100m even i'd get ahead on start, but still having PB at 11.13 even tho, that was 10 years ago before i went to army and i never participated on any trainings, just football background but i guess i'd have had chance to make it for something like ~10.50 with proper training. 400-800m works way better for me, would be nice to try and get below 50 seconds before i turn to 30, still that ~51 is what i did 10 years ago remains as a PB on 400m.