Hello this is what I think an average healthy 20 year old.male would be able to achieve after 1 year of specific training 100m: 12.2-12.7 sec
200m: 26-27 sec
400m: 58-60 sec
The average person doesn't have the natural speed to achieve better times within 1 year of training. I am 17 years old and without any previous sprint training my best 100m time is 13.33 sec on concrete without spikes actually handtimed 13.08 sec and added my reaction time. A healthy 20 year old male should be way faster than me after 1 year of training if not it means that I have way above average fast to slow-twitch fibers ratio.