It's very hard to start an aloe vera by leaf cuttings but if it is off why not try.....make it a clean angled cut. I would leave it dry out on the counter for at least a week. Then use rooting hormone, ground cinnamon or honey on the cut, dried end and stick it in a small pot with good potting soil. Water and let it dry out before watering again...
The main plant looks like it could use a new pot or at least new soil. Don't make the pot too large....