I'm just bad at everything and don't have any skills.

I mean.. that sounds like a legitimate reason to not extend you an offer.

But it's good that you know this about yourself and can hopefully formulate an actionable path to improvement!

I'm just going to coast/struggle at my current job.

You might not like this answer, but I was once in the place you are now. The only thing that will change the situation for the better is to invest in yourself and learn new skills. The problem is motivation and time. I know how discouraging it is to come home exhausted from the job you hate, eat a quick dinner, and hit the O'Reilly and Addison-Wesley books to learn that new programming language. But eventually it will pay off.

I've found knowing your limits and avoiding getting over your head is a very valuable skill to have. Cause if you've worked with someone like that you'll see how bad not having that is.

Tip: There is always someone better at X than you are.