Tricon, if you are writing, the chances are good you'll improve with each book. This isn't to say your first book isn't worthy! The agent and editor market is really tight right now. It's okay to wallow in a bit of despair, but temper it with some dark chocolate and the caffeine beverage of your choice. Then get back to work.
Sometimes, first novels benefit from a time-out. That, I can tell you from experience.
I've worked, off and on, with one big novel since around 1998 (though I did set it aside for nearly ten years until 2009). I thought I was ready to query then, and blew through 25 agents. My query letters were horrible. I re-worked them. Still no takers. I entered part of the mms in a big contest, and it won a higher-level honorable mention. Then I entered the whole mms in a big publishers contest, and it won third place. Tellingly, it did not get an offer - it was too big, and the senior editor told me it was lovely but it needed work. By then, even using the contest honors in my queries, I'd gone through nearly 70 agents, with only two partial requests and one full request. No sale, each time. And the agents/editors mirrored the opinion of the first editor to comment.
Swallowing my pride was really hard. But I finally understood what they'd been trying to tell me about my baby. It wasn't ready.
So I backed off. I wrote two short stories, and they sold. I wrote a new 99K novel in a different genre, in three months of working time. I sold it within a year of starting to write it. I used that sale to get the notice of an agent I could never have approached on my own. She's not my agent, yet. I still have to whip that first big mms into shape, but at least she's consented to take a look at it.
As long as you are diligent about writing and open to exchanging pride for learning experiences, your work will improve. Don't give up, and don't succumb to too much bitterness.
