kevo you're a smart guy
you may understand a lot of smash things on a conceptual level from analyzing video and reading, but you gotta play a whole lot to really integrate game knowledge to the point where it's instinctual and you don't have to stop and think about it. plenty of good players (read: all of the first generation of pros) weren't/aren't good so much because of the information they got online because there wasn't as much as there is now, they were good through empirical knowledge (an assumption but i dare you to disprove it). in fact it could be argued that smashboards/other information have somewhat of a detrimental effect on creativity because kids will copy what works and not solve problems themselves...copying is generally good as long as you comprehend why something's good and have the mindset that what you're copying has room for improvement and isn't optimal. in the moment you can't intellectualize situations, at a certain point you have to "feel" what to do due to the speed of the game and that's what is so attractive about melee to many of us, specific improvisation with a general gameplan, as opposed to brawl's more specific gameplanning and methodical execution, which appeals to a different kind of person.
gotta practice your techs so what you're thinking can translate into what your character is doing, that's the most frustrating aspect for me
i'm definitely not gonna show my face at any tournaments until i can go around even with my training partner who does go (hypocrisy with my final paragraph lol). i don't have exceptional natural talent (decent reflexes/vision, pretty un-dexterous sweaty small hands that aren't great with precise inputs...no johns), but i have a decent analytical mind, which is apparent in you too from reading your posts. so i know i'll never be the greatest since greatness requires both natural talent+hard work, i just want to not suck.
tl;dr don't give up unless there's nothing you enjoy anymore or it's not worth it from an input>output standpoint, we're the future of smash. it's accepted that you're gonna suck at whatever you do when you first start doing it, even eating (...literally babies sucking on teats...), it's just that smash has a pretty damn high learning curve, so don't worry about what people think of your gameplay, worry about what people think of your attitude. sounds like you've got a pretty good mindset which means results will eventually show, i hope this post can be that little boost to push you to the next level.