Hey, I'm so sorry you feel that way - you put so much effort into every application, so it makes sense to feel disheartened if you don't get your desired outcome. As others have already said, some people have had to go through so many application cycles to get an offer. But let me give you also my view on this.
1. Getting a training contract or not says nothing about who you are, let alone how skilled you are or how much you are worth. I don't mean to diminish the achievements of anyone who has secured a training contract in saying this, but law is simply what you do - it's not who you are. Not getting an offer doesn't mean you don't have all the skills it takes to be a great lawyer - don't forget that grad recruiters just see a snapshot of who you are, and they are human too with their own biases and beliefs. Just because they haven't seen your potential so far, doesn't mean you don't possess it. If you get rejected by a firm just say "okay, they didn't see my potential, that's their loss" and then think "is there anything I can do to better reflect my fit in future applications?"
2. I can understand what you're saying about that odd feeling when you see your juniors succeeding in the process. For context, I finished my law degree in 2019, did a masters in management, and have been working at one of the US banks ever since. I sometimes find myself in that strange feeling of "oh, I'm up against second year uni students....". It's only my first proper application cycle (have only had finance/consulting professional experience so far), but I already know that I'll have to fight these types of thoughts if I face rejections. What I'd remind you - as I'll have to remind myself - is that everyone is on their own timeline and you're not competing or trying to keep up with anyone. From the looks of things, we'll be (sadly) working till our late 60s, maybe even 70s (!!!). You're not running out of time - you're just on your own path.
3. Law isn't the only option - I'm not saying this to discourage you, and I'm not trying to implicitly tell you to give up on law. But the way I see it (admittedly as an outsider for the most part), the application process is so unnecessarily long and complicated because of the sheer volume of applications, the hours are incredibly long, and the work isn't always as important or meaningful. I always keep in mind these negatives to avoid romanticising or obsessing over becoming a lawyer - it's just a job, it's not an ideal job in any way, and if I don't get it there are so many other options. I'll sometimes tell myself "huh, am I really begging these people to give me the chance to be worked to the bone?"
Sometimes we think we want something until we do it and then realise it's not how we imagined it. Now, you might still say "okay, but I still want to be a lawyer", and that's fine - that's where I stand at the moment too. But try and avoid romanticising or idealising the legal career, and that will hopefully help you consider alternative career options and put less pressure on you to succeed in law applications. I was told by someone once that you should try and "maximise your luck surface area" (because there is inevitably some luck involved in all this, I think) - don't put all your eggs in the law basket since there's so many other options out there, and remember that the law basket isn't necessarily the best one out there. I acknowledge of course that I'm saying this from the rather privileged point of working in a well-paid finance job, and you might have different pressures to get a job.
4. You can be proud of the process even if the outcome doesn't follow - even if you don't get an offer, still have pride in the fact you put effort into an application and made it as far as you did in an application process (even if you didn't make it past the application round). Applications take time, and you put in the time to give it your best shot. So be proud of yourself for putting in the work, irrespective of what happens.
I hope some of this helps