Not too late to start running & get very good at it. Most start running in the US at 13-14. Thing is, the good ones usually run something like sub-17 very quickly & off of very low mileage. Then they're under 16:00, maybe even 15:00 for XC by the time the graduate HS.
Others might need a decade of training & high mileage to run 15:59 for 5k. Everybody is different. Some of the examples given were of people who did quite well after being elite or close to it in other sports. Your swimming background should help. If you take to running, maybe you should consider triathlon.
Running is about how much you're willing to do to some extent. Start putting in the miles & your times will drop rapidly at first. How far they'll drop is anyone's guess.