Aluminium corrodes:

in humid conditions a thin oxidation layer may form, which actually protects the material underneath.

It’s not true that it’s not magnetic:

it’s what’s known as paramagnetic, meaning it creates its own induced internal magnetic field, which is then added to the externally applied magnetic field when brought into close proximity with another material. If the external magnetic field disappears, the magnetic field of the aluminium disappears, leaving no residual effect.