It's not very important, but we generally call them "games," not "matches." In chess, when we talk about a "match" we usually mean a series of games between two opponents, like the Carlsen - Caruana world championship match. As I said, it's not that important, but people will probably understand you more easily
Match Review
I'm likely of the same age as you. Nowadays some of the younger folk raised on internet chess and especially on blitz and bullet disagree, but many (I believe most) still believe that you can't easily get stronger at chess without playing longer time control games and using the time you need. The idea is that by doing a full thought process, however long it takes, you get better at doing the full thought process, and can compress it later when stronger. By contrast, if you are playing blitz, you dont have time for the full throught process and don't get that training. On this view, blitz is mainly for fun, and not training to get stronger (and bullet may actually hurt your strength).

Qualifications: Similar situation as far as many years away from chess before returning and wanting to understand the game and the purpose of moves better.
Elaboration: You aren't giving yourself enough time to think. But without a good process to follow, you'll never have enough time.
Find a process, follow it, improve your process.
Take the time you need to follow your process and improve, then you might need less time as it becomes almost automatic thinking.
@TumpaiTubo - damn man, so sorry to hear that. Well if you just want to have fun, the best way to improve doesn't matter. You can excercise your brain doing blitz, and if its fun, then its fun. If you want to improve as much as you can, I do recommend human lessons. There are some people that advertise here and a dude I grew up with, my best friend for many years, is a strong IM and author of about 8-10 chess books. He is doing individual lessons and has some group lessons for diferent abilities as well, all by zoom.
Finally, screw those doctors. Fight the good fight.
P.S. PerpetuallyPinned was raising another one of those beginner principles that can help you. Its generally bad to make a lot of pawn moves in the opening. As a beginner, its best to make pawn moves that claim a piece of the center or help you develop your pieces, to develop fast and castle. As with every beginner principle, they are over simplifications, but not in this case - 2. g4 was a bad move for several reasons, and the beginner principle would have helped you avoid it.
Yep, slowing down and sort of being organized about it, looking at all checks and captures for both sides, make sure you count all attackers/defenders and consider there value when thinking about captures, considering not just what you want to do, but what your opponent wants to do and might do in response to what you do. Some trainers break it down specifically, but I think the thought process is mostly common sense.
Long time controls can be hard to play on the internet. Of course, 30 minutes a side wasn't remotely considered a long time control in the old days, but nowadays that counts as a long time control yes. Maybe add a couple of daily chess games, which would be the equivalent to play-by-email for us old timers. Its an option under the play menu.
I have no idea what all of those things are, but congratulations on a life well lived so far. Keep it up.

You might find some of the resources in this forum useful:
https://www.chess.com/forum/view/for-beginners/middle-game-strategy
If you realize a need for a process, we use them (even subconsciously) for almost everything. Basically habits.
The older cars you had to pump the air pedal twice before starting. Some call it a gas pedal, but controls air flow. Nowadays, you might have to have your seatbelt on and foot on the brake for it to start.
You probably had a breathing procedure to follow in your shooting sports before muscle memory does it on auto pilot. Your martial arts maneuver might require thousands of repititions before mastering. My son has a 2nd dan in Taekwondo and a 1st in Hapkido.
I even have a specific procedure for using a public restroom.
I looked at a few games, and would say that you are playing at the level of a fairly new beginner. I don't know if you got much further than that back in the day and have some rust or whatnot, but that is what I'm seeing. Perhaps you are a little stronger than your rating in the 500s but not overwhelmingly so. Any player with that rating needs to focus on learning beginner principles and learning a consistent thought process to not blunder, and to spot your opponent's blunders. And this is indeed what I'm seeing in your games. You do seem to know to develop your pieces quickly, and developing quickly and castling to safety is probably the most important beginner principle, but you are blundering quite a bit as is to be expected.
In terms of how to improve, pursue beginner training. Human training is the best; but if that isn't an option even posting your games here can help. Absent human training, you need enough fundamentals that I might start with a book or internet course. Unfortunately, I don't remember which books are at what level -- like Bobby Fischer Teaches Chess is a famous one, but that may be starting at how to move the pieces, I don't recall. Jeremy Silman is a noted trainer with a lot of books, but I'm not sure he has anything at the right level. These days of course, there is plenty on the internet, but I'm not sure what to point you at. Hopefully someone else can help more.
In terms of not blundering, some of the books will cover a through process to go through for each move, but practicing tactics is very important as well. You are a premium member, so you have good options for getting tactics puzzles here -- go to the puzzles tab. I also recommend chesstempo.com. One thing about chesstempo, might also be true here, is that it starts by serving puzzles at a level that will be too hard for you, and will only adjust downwards after you fail a bunch. Some of the modes that chess.com has might be the opposite -- like for puzzle rush, you might only be able to do a couple then it will get too hard. Don't be put off by that, its normal.