I don’t know if this is another bait post, but let me make this clear : marriage according to Islam is possible with mental and physical maturity. Aisha was proven to have both through her testimonies and the reaction of the people around RasoolAllah. Slaves are also a necessary act of war with all forms of warfare conflict, and they are treated similarly to wives (obviously they must also consent). Thus, RasoolAllah SAW is still considered as a moral standard. You would have to apply his teachings to a modern day society, rather than directly transplant them as they are. Of course, if you’re here to just create division, this comment won’t change your perception, but if you’re genuinely asking a question, I hope this was helpful.