Look, I understand your frustration, I felt like that for a while. But honestly, everybody has ruts, and it's hard to get good. That's why most people aren't good.
But, give it time, the first major hint I'd give you is have an attitude of winning. I mean, don't set yourself up too high, then you might be disappointed, which hurts. But expect to do well, otherwise it's self-fullfilling.
Beyond that, observe, it's all about observing people.
Also, practice. Spend time in neo's hyperbolic time chamber, I notice with your marth you seem sloppy with your zoning techniques. Personally, I spent some time just practicing them and I got like 20x better over the course of a few hours. It works.
So yes, you can get good.