Does it matter if a non-Muslim knows how to fight or not, in Jihad at Talab?

So we all hear that Islam prohibits against fighting civilians. I’m just trying to understand whether that’s a modern term in terms of Islamic jurisprudence or not. To my knowledge, only men who are of age to fight are allowed to be k*lled if they refuse Islam or Jizya (if they have the option of Jizya). So, is permissibility to k*ll based purely on status and capacity (being an able-bodied adult male) alone and is enough of a reason, or does actual ability to fight matter aswell? In other words, does Islamic law consider every adult man a lawful target regardless of whether he has any fighting skill or combat role? I’m asking what type of grown up, healthy men can be fought and k*lled.