Loki said he was joking and it was to piss Luffy off. There is no reason at all to believe Shanks used deception or jumped him with his crew, and until the manga gives reason to believe that, I'll stick to what it says, which is that Shanks beat Loki.
It literally is a gender based title lol, it is "世界最強の男" and "男" is for the male gender. If the title was World's Strongest Human it would be "世界最強の人間" since "人間" is for humans. And I don't understand your point about how "none of the other titles are gender so this one can't be!", Mihawk's title is for a combat style and Kaido's is for living things as a whole, there is no relation between any of them at all.