That's why you need backup

Yes, but humans can run for longer.

Also those are averages

Also those are inaccurate regardless. The average human JOGS at 8ish mph, and maximum recorded human running speed is 28mph, so the average RUNNING(/sprinting) speed of a human is like 14-20mph.

Also it isn’t about out running the chicken, it’s about out maneuvering the chicken. Using agility, endurance, and smarts- you can cut the chicken off. It’s generally not a wise strategy when “hunting” to run straight at a thing unless you’re adapted for such feats of speed, like a cheetah- which even then given preference will try to outsmart rather than outspeed.