First, make sure you're regretting the actual job, not your dream of what your life would be like today if you had stuck with the perfect first job and nothing had changed. Force yourself to recall the warts on the dream -- the annoyances that have faded with time, the frustrations that made you open to change. It is so, so easy to idealize what we have lost, particularly when we are not happy where we are now. But all that does is sell yourself a line of self-pitying crap. Worse, it persuades you that there really is some ideal job out there, and so it's ok to keep wasting time dreaming about it, vs. figuring out what combination of pros and cons is the right balance for you.
Second: to the extent you have a realistic view of the good and bad things about your former jobs, your regrets are telling you that your have been making decisions that are not aligned with what you truly value. And that's ok -- humans are absolutely notorious for thinking that the wrong things will make them happy. So it's actually a good thing that you are feeling this, because it gives you a chance to change course and make better decisions going forward.
So: what drove you to make those mistakes? Well, as others have noted, fear just jumps off the page. You seem to have a high degree of need for security, so that the slightest threat of change was sufficient to trigger a desire to jump ship to something safer. This is actually really good news, because you know what is the best security of all? FI! Not needing a job allows you to wait and see if things change for the worse/better. So the takeaway here for the short-term is to build your safety net outside of your job, i.e., lower your expenses and build up a big fat emergency fund so when that fear kicks in, you can remind yourself how illogically you are acting, because you have plenty of cash and low expenses and can afford to ride this out. Added bonus: as you're discovering now, the more solid your current financial situation is, and the closer you get to FI, the less important a bump in pay becomes in your decisionmaking.
The other thing that you seem to be discovering is that security and money do not always provide a satisfying job experience. Some jobs are flat-out boring. Some jobs have a crap team ethos. And some of those crappy jobs offer money and security. But again, this is good news: you've identified this as a problem, which means you can teach yourself to move past the apparent money and security and look for the factors that make a difference to your daily happiness once you're actually in the job.
So the next step is figuring out what those are. Why do you think you enjoyed that first job -- what was it about the actual work and the environment that got you jazzed? What skills did you get to use/develop that you aren't getting to use now? Or was it the training, type of work, management, independence, etc.? Think about all aspects of your former jobs and see if you can tease out the things that you liked and disliked. And also don't discount the money/security issues. Leaving that first job might have been the right call for you at the time, if you were in a different situation and needed the paycheck. The fact that Current You wouldn't make the same decision today doesn't mean that Past You was wrong.
Once you figure out -- as best you can, we're all imperfect -- the things that make you meaningfully happy and those that don't, take a look at all of your options. You are not stuck where you are now. Can you go back to the last job? What are the pros and cons of that? Or if you're really pining over the first job, can you see if there are opportunities to go back there? Even if none of that is an immediate option, do the things you can do to set yourself up in the future -- keep those connections active, let your friends know you'd like to come back, build your network, build your skills, be an active driver of your career.
Or: decide that you actually do get enough from your current job to be content there for as long as you need to reach your financial goals. And then repeat the analysis any time you are once again unhappy.