If you are describing what happens to people in general, you need to use non-gendered text. If you are talking about what would happen to Frank the Barbarian or Melinda the Ranger, you can use Frank or Melinda’s gender. Frank and Melinda also have players: Tony Corman and Sandy Giles.
I find that specific examples not only make the rules easier for my readers to understand, they also make it less likely that I’m going to make a mistake. Going from generalizations to specifics brings an immediacy to both the writing and the reading. I recommend placing some example characters in your text and using these characters as your examples throughout the text. Your readers can refer to these specific examples and see how your rules work “in real life”.
“Frank the Barbarian’s 16 endurance means that Tony has to roll 16 or more to survive the spiked pit. If Tony rolls 16 or more, Frank takes 2d8 hit points of damage. If Tony rolls 15 or less, Frank dies.”
Always make sure you know whether you’re talking about the character or about the player!