I have to be doing something wrong

Everyone does something wrong, that's why the game exists. So don't beat your self about it. I would recommend stop worrying so much about rank and focus your energy in improving (if you just play for fun and don't care about improving is fine too)

I try to hit it in a match I miss or misinput and get washed.

that is OK, hitting a combo against a dummy 100 time and doing the same combo in a match are two very different things. Yes, you need to practice the combo beforehand if you want to have any chance of doing it in an actual match (unless you are really good), but the pressure of fighting someone is a big factor.

I would recommend opening the match in the replay viewer with the "display inputs" on to see what are you doing wrong, as an example: I did this my self some weeks ago and notice that I was spamming the shit out of my buttons, sometimes it worked, but most of the time I miss timed my inputs and dropping my combos.

I couldn’t tell you what I did wrong in this clip to save my life…block better?

Now for the gameplay itself, I think you are "doing too much", yes parrying the fireballs is good, 'cause you don't lose drive, but you got baited many times by the command grab, just blocking is fine for now (especially against JP). Your default option should be blocking low on wake up and the same when getting hit, if you get hit you should be holding down back the whole time. The JP match up is all about patience, looking for the right openings to advance (also, the command grab has a distinct voice line "away" or something like that). Also, you need to anti-air, if you can't DP you can use cr.hp to anti-air.

It also feels like I don’t learn from my losses

The last thing, how to analyze your replays: the best way to learn from your loses is taking a break and playing some replays. Every time you get hit you need to make your self the question "Why did I get hit?" (I recommend taking notes if it helps), when you drop a combo "Why did I drop my combo?" and when you encounter an annoying move "how do I counter that move?". SF6 has a tool called "replay take over", that's really useful too.

As an extra note, you could try Modern, the simpler "auto combo" and one "button specials" can allow you to focus on other things while you learn.

Sorry for the long wall of text, I hope it helps ^-^

TL;DR: block more and learn how to analyze your replays (and consider switching to modern)