I was going to go on about how humanely ending somethings life is an oxymoron but i let that out on somebody else today lol,
there are so many methods, my old step dad would walk up behind a chicken while it was scratching and pecking and knock its head right off , instant death, a nice size stick or dowel will do it, my neighbor will pet the chicken than snap its neck quickly once its calm. most people will say the use of a butcher cone would be the most human but thats only because they dont have to watch the body flop around so its easier on the butcher. you can kill it and leave in in a cone to drain blood for a while if you kill them any other way you have to wait for them to stop jumping before you hang them for draining. A butcher cone is what most hand processing facilities use.