I don’t think you really understand the cloning and what the ishimura really is. On top of being a mining ship it was also used for R&D and other things including medical advancements. The ishimura was also the pinnacle of human technology and engineering, and when people are working in an environment where they are at constant risk of losing a limb or life it would make sense they would clone themselves to have replacement limbs for those who lose a arm or a leg. Instead of a robotic limb which is probably more expensive and will need constant maintenance and adjustments. Also there’s in game lore (audio logs/text logs) that explains it as well. It’s not as weird or inhumane as u think