Proxima B is orbiting a Star that is extremely unstable and known for massive flares (all red dwarf stars are flare stars), and the habitable zone of a red dwarf where water is likely to be liquid is far closer to the Star like almost the orbit of Mercury close. Not survivable for carbon based life forms based upon DNA. A very stable Star like Sol is the best place to look for Worlds where Carbon based life forms using DNA can possibly survive. Any planet must also have an active magnetic field, so it needs a liquid metal outer core and active surface volcanism to generate enough atmospheric replenishment to make up for losses due to Solar Winds. It will also need to demonstrate free Oxygen in the atmosphere indicating chlorophyll and plant life converting CO2 into Oxygen in an actively renewing manner. Habitable world's for Humans and Earth type plants and animal life (the only thing that are certain to be edible by Humans and Earth animal life) are going to be extremely rare. It takes much more than being in the Habitable Zone to make a planet habitable to Earth life.