You're pretty young to know what you want to do with your life. You're trying to answer questions you won't be in a position to act on for many years. Taking prerequisites is important for keeping your options open, but who knows, you might end up liking political science and become a diplomat. Meaning, you're suffering from anxiety, and you're focusing this anxiety on school right now because that's such a prominent part of your life. You might also be getting pressure from your folks and your peers. You have to learn to be whoever it is you are, not what others are. That's unpleasant, and it doesn't work. I think talking to a counselor might be a good idea so you can learn why you're anxious, not so much why these specific things are the focus of your anxiety. And I'm not the doc, I'm sure he'll have better advice, I'm just an old fogey and believe me, we've all been there, and you'll find life will be very surprising.
You both have something to offer, but your skills will bring more options. Common sense is great, but the ability to learn, and the desire to learn, is very valuable. Again, I don't think your problem are these specific things -- you are who you are, your brother is who he is, and the world needs both types. Absent mindedness is also common, especially at your age when you're thinking of a million things at once and doing two million. If you're getting good grades, it means you can focus whenever you want to or need to. I think the problem is you're worrying about things for some reason, and talking to a professional will help you figure out what it is.
thanks for the comments, they are truly comforting. You sound like you know what youre talking about and for that reason i would like to continue to talk about it. I feel as though i have a hard time concentrating. I am very absent minded, despite my best efforts. (For example just yesterday i left my mom's headlights on and the battery died.) Im pretty sure that most of if is due to stress but still ive never felt competent at simple jobs. I used to have a job but i was not very good at it. On the other hand, my older brother can start a job and do well right away. While he may not get the highest grades, i feel like this type of intelligence is much more valuable. In the future, i feel like people who are smart like my brother, who have common sense and foresight, are better off than people who just get good grades like me because they will find a way to survive.
You have just received perfect advice from Paxiled...I have nothing more to add except to highlight what he has said..this is not about making a real choice, this about being anxious and eager to perform in order to mollify your self doubts..that's where a counselor can help.