Sub...most of us go through periods of feeling insignificant and small, and not belonging. I've struggled with it all my life. I have found that no matter what I'm into, or try to learn, there is always someone else who SEEMS to be a little further along, or a bigger giant, or happier, or whatever. In reality, it's that way with everybody...everybody experiences it in different degrees. It's not healthy comparing ourselves with others, but we all do it seemingly naturally. Try not to compare your self with others to your own defeat... It's not always easy, but you are your own person, and deserve to think good things about yourself, and others....hang in there...this too will pass, you will get over it and be tested and tried and become mature...in your own time. Reality is not always what it SEEMS at the time.
A lot of it is in how you talk to yourself on the inside...get in the habit of saying good things about yourself to yourself ! It's your choice.
That's the best I can do in this situation, and there's no room for snarkiness, or humor, or any thing but understanding here.
I don't know what more to say that would be appropriate...

First, you're not inferior to anyone here. We're all intelligent in some aspect and all smart when it comes to one thing or another. Just like at all the opinions being thrown around in here already, some of them I think are horrible, some are okay. Some people in this thread might be thinking they actually are experienced in something they can't be because it's different for each person (talking about three of you specifically!). So they are just like you, inferior..and also not inferior. So no worries about that man.

As for motivation. I had the same problem, for 4 years. But you will get the motivation eventually. Sometimes it just takes being at the very bottom to finally bring yourself up.

I'm also not a people person and I can stand very few people after a short amount of time. I don't like hanging out with anyone usually and it's better for me that way. Because people have opinions and won't budge when they're wrong. I'm not right all the time but in my experience over this past year, the people I talk to about certain things..when we have a disagreement on something I'm right about what I'm saying the majority of the time. Mostly because I usually only choose to talk about something I'm actually educated in.

Anyways it sounds like you need to spend some time alone in the world (so to speak, keep family close obviously) for a while to give yourself some adjusting me time.

Don't underestimate thinking with emotion and passion rather than cold logic. I'd trade you some logic for some of that passion if it was possible since I've found some of the most creative people I know to be the emotional types rather than the logical types. The type of person who would sooner think "Oh this would be awesome in a story!" than "I wonder if I could make this work within the predetermined restrictive boundaries of my story."

Also there are two or even more sides to smarts. There is intelligence and then there is wisdom. I take it you are only looking at how intelligent the people around you are but not how wise they may be. To take an example I have a friend who is really intelligent but far from being wise. He's on a speed course in college taking two semesters at the time I take one and he took 7 courses in maths over the course of two years! And that′s along with taking all the other classes he takes. Basically academically he's superior to most people I know. Yet for some reason this brilliant person is letting himself fall down the path of drugs. It isn't because he doesn't know what they do and what they contain. He could easily name half the chemicals in what he takes. He just does it for some reason that has no logical reasoning behind it, it maybe makes him feel good for a while but it doesn't change the fact that what he does is stupid.

You sound like the kind of person who is capable of taking a step back to reflect upon yourself and think about things deeply, at least given the time to do so. So honestly don't just think about how much more intelligent people may seem to be than you are. You probably aren't that far from their own level anyway and even so there are other things that determine your worth than intelligence and even wisdom. Getting into a bit more of an RPG style spreadsheet way of thinking you also have to consider what other things you may be good at. I have a cousin who is doing worse than I am in school and he has made some poor choices too. He′s 4 years older yet a year behind me on his college studies, not to mention he's made some poor legal and financial decisions. But it doesn't mean I think he's inferior in any way and I wouldn't think that he'd think that way either. Where he excels is in charisma. He's the kind of person who can weave people around his fingers with words and he's not afraid to use that to his advantage. I'm often quite jealous of him since I′m not as outgoing and capable of making what I want to happen actually happen. For example he's been playing D&D for years and it just took him a bit of time to get his friends to get involved in the game with him and suddenly he had a large and stable playing group. I however want to play some D&D as I like the series but I don't even have enough friends (I normally only hang out with a couple of people at a time) for a good playing group and I don't find myself managing to get into any playing groups. He on the other hand in my position would quite likely be capable of getting into a playing group in a flash.

Basically what I′m getting at is that there is a million and one way to be amazing. Even if you don't think you're as capable as others that is only because you are focusing at what they are good at, not what you are good at. Problem is we normally don't see all too clearly what we are good at ourselves because we take our skills for granted when we have them. I myself am not even sure what I′m good at. But the question is, where do you excel over others ?