Is the quality of work done in PhD a measure of my abilities to pursue academia?
I think you are overly harsh with yourself, actually. There are several things going on here. First is that you are now more mature intellectually than you were when you began the work so are more likely to discount it than others might be. You know it best and if you were starting now, with what you now know, you would start higher up the ladder. That is just growth. 

Just as important to answer your wider question is that for successful academics their first work, the dissertation, is seldom their best work. The more you work, the better you get. Just like an athlete. 

I'm impressed, actually, that you taught your advisor something about your methodology and, it sounds like, developed that yourself. 

But, the work doesn't get easier as you go along. It is just as hard, but you gain additional insight into the nature of things, especially that which it is important to study. I'll predict that if you don't give up you will do pretty well. A bit of letdown burnout is pretty common at your current stage. Power through it.