I wonder why they didn't teach you what these hadith , prolly so you dont have doubts or you know how bias people can be. Only telling you what you wanna hear.I have studied the Seerah of Prophet Muhammad pbuh. I got to know his Biography deeply, where i can associate his actions from others actions.
In the Seerah during Islam conquering pagan Arabia tribe, Killing of men rarely happened, killing mostly happened in the battle fields. Men were taken as prisoners yes, and they were given the option to convert to Islam or pay for their own freedom and go away to other lands. Unless they were cruel men who killed alot of Muslims, then they killed for sure
Lets start with the worst,
There is more and more. They forget to teach you the important side of him. if you need more, don't be shy to let me know or if you got any question on those hadith or need a little expiation on those hadith