How can I answer questions from non-Muslims regarding: the ruling on gelatin, the reason for the prohibition of pork, and the reason for the prohibition of meat from animals slaughtered in an un-Islamic manner, while providing scientific evidence?

A Muslim should not exhaust himself by searching for the wisdom behind a prohibition after having accepted the ruling. For everything that Allah has prohibited, there is a wisdom and a benefit that accrues to humankind. The legal principle regarding what is permissible (halal) and what is forbidden (haram) is that what is good and beneficial is permissible, and what is vile and harmful is forbidden. Carrion and pork are among the vile things that Islam has forbidden due to their obvious harms. Gelatin extracted from carrion is forbidden due to its vileness, whereas that extracted from a properly slaughtered animal is permissible. As for pork, its harm and impurity are confirmed.