How to stop being stupid?

I am a stupid person though i am getting more stupid day by day now.I have always been stupid i even got told by people i know.For example;i realize things way too late you know the people that understand everything at the moment instantly ,know what's going on,aware of their surroundings.People can't lie to them if they do,those aware type of people will realize instantly.I have always been told dumb,clueless etc... i also have a problem with critical thinking and comprehension skills.I just want to get better at those things.Even if it's not possible.Any advice welcomed.Thank you so much.