When you think of it, there is not one single way to define this, it is almost a "hypothetical", and "hypothetical" rely on opinion.
I can only speak for my opinion, yet hear me out. When people tell you that babies are dumb, it is because they have not experienced or have any memory of a topic. As they get older in school, they will have memorized certain patterns in that subject.
Your mind will develop around this using memory. For people you refer as dumb, its not that they are dumb. They haven't memorized that topic or is having trouble. Yet people only refer this in school. Like if someone was a nerd, they have memorized more than other people in a specific topic.
When you think of the definition of "smart", it is not wrong is some, but right in others.
IQ means nothing, it only tests your logic reasoning and not even most of that.
But, what I am going on here is saying that people have different goals in life, people will see it in other ways. Complex for one and viewing in another. But people will be have memorized more in one subject. When you think of this, you could know a lot on a game or sport or movie. Yet when you include the person who knows the most in one category, they will know the least in the other. So it will balance out in the end. And natural talent, that only gets you so far.
Don't be afraid for who you are, cause in the end, you are you and you will only experience you. Everyone sees life different.
There are many ways of being smart, but there is also many ways to view smart.
People before us (Please do not bring reincarnation, or any other possibilities of outcomes for afterlife into this.) structured how we "should" view the world (Which is a piece of s***). So, according to their personal views, which became widely known, it is not wrong.
I personally believe that smart does not exist, you could say our experiences made us wise and knowledgeable (Experience and wisdom is not ageist) which is somewhat true, but there are many other things conflicting with that.
On the other hand, I define smart as someone who is not afraid to be themselves, someone who does not care about his or her own ego (Key to happiness), someone who really understands that life is quite complex to figure out, but easy to live, someone who knows most of their problems are emotional, not that's a bad thing, but you could always find the pointlessness in it. (I'm not bias, i have two sided views, and percentages as well, which is usually 50/50.)
So, society’s opinion on the definition of "smart", is not wrong, but CAN be wrong to someone else’s standardized view.
Another thing, it is possible that we are taking the word “smart” too much into account, and forgetting that we do not have to live up to that popularized, trendy word. Smart can simply mean being proficient in academics, while a different word such as: “Quib“ (made up/credit to my friend Jay) could mean exactly what you’re misusing “smart” for.. Kind of like the improper use of “literally” and “Mature”. Instead of trying to change the definition of words that will adjust your views, make a new one, make it popular, publish it, and you have yourself a deal. You just added more words to the English language and even other languages! You also made yourself go down in history.