The word good is subjective. For some people, it means better than fine but not as good as great. For others, good is the best you can strive for. It's one of those words that is completely context-dependent.
If someone says, "How are you doing?" And you say "good," that can mean almost everything. It could mean that you're genuinely doing well and you're happy to say so. It could also mean that you'll say whatever you can just to get the other person to shut up. If a server asks how the food was and you say "good," it could either mean that it satisfied your needs or that it was the most disgusting thing you've ever put in your mouth but you were raised not to complain. So when people say someone is a "good person," it has almost no meaning it all unless you have more information. But trust me when I say these memes are good.