Its close, but good and evil is more than just the selfishness/selflessness scale. Good is about the best result. How can people be happy without impeding others happyness? Where is justice? A good charecter strives for that result and indeed, often they dont mind sacrificing themselves in some way to achieve it. They know that even though their personal state might have worsened, they have improved the world as a result.
Evil, on the other hand, isnt just about putting yourself first. Oh thats part of it, but its also about cruelty. About not just being able to cause pain to others, but actively wanting others to suffer. Perhaps because it gives you joy, or perhaps you just dont care what you do to others as long as you come out on top. But the essence of evil is not just that you are out for yourself, but that you are not only willing but eager to harm others and watch the world burn to get there.
And its worth noting that alignment is a spectrum rather than hard definitions. The distance between a selfish neutral character and an evil character is often very small, as is the distance between an evil character who thinks they have a good reason to be evil and neutrally.