They can be. Plenty of 16-olds still in school and also a member of Hamas of Islamic Jihad outside school hours.

Every Zionist in Palestine is a valid target. They’re on stolen land.

Ok, so now you just actually called for genocide. And by that logic all US citizens that are not Native Americans are valid targets in another genocide. Of course, since the UK has been re-invaded many times, all UK citizens are now valid targets for genocide. The palestinian arabs were also invaders according to this logic, so also valid targets for your proposed genocide. Etc. etc. You're calling for genocide of everyone.