Okay there's a lot to dissect here.
1.) I know it won't matter, but you don't need to be perfectionist in this game. Unless you plan on being #1 in the world, you will always make mistakes.
2.) I've noticed you always talk about wanting to get better. If you want to get better, you will at times need to change your playstyle. This game is founded on mix-ups.
3.) Charizard has a super-armor up-b and an extra jump, you don't need to worry about missing the ledge. Just make sure you don't burn your resources and you'll be fine.
4.) Off of throws, almost nothing is true for 'Zard, but having a 50% chance of more damage and more pressure is always better than a 100% chance of less damage. This goes double since you're staling Charizard's main kill throw.
5.) Being aggressive is never inherently bad. Of course there's always a time and a place, but I'd say in this game in particular being aggressive is the way to go. Charizard does struggle with frame data and being punished, but he has the movement speed and power to make up for it. Being aggressive causes your opponents to make more mistakes, it's just on you to know when and where to be aggressive.
1) It seems like I make many consistent and idiotic mistakes. Either way, I can't bring myself past them because I get so tilted by one-sided MUs. (trolling Isabelles are what made me throw in the towel.) Maybe if I quit quickplay...
2) I try to mix-up. I forgot move decay was a thing/important.
3) I'm aware of these two things; I use them to recover from under the ledge. (It even saved me from a charged Waft that should've killed me lol) Flare Blitz is a panic tool of mine if I think I'll get gimped or edgeguarded.
4) Again, I forgot about decay. And here, it seems I take Charizard's movement speed for granted, as I almost never take advantage of it.
5) So I know that now, but what about playing it safe? How would one optimally do that? I tend to forget that roll decay is a thing now.
But yeah, despite putting emphasis on "quick", quickplay might not be for me. Maybe I should stick to Anther's Ladder, etc. I have no interest in locals or above, so AL could possibly benefit me. Either way, I still want to have fun with this game, and quickplay isn't doing it. And of course, I'll continue to lab these skills and tactics I learn from advice/pros/etc. in Training.