The hardest part about getting out of Bronze 5 is admitting you belong there.
This will be a longish post, but it is honest advice that I wish someone would have told me instead of simply saying "get gud" or mock me for being in Bronze. Please take it to heart because from someone who has hit the rock bottom of Bronze 5 before and never looked back, it will legit help.
With that being said:
I'm not a challenger god, but I belong where I am (Currently Silver), and when I was in Bronze I belonged in bronze.
The main thing stopping people from climbing isn't skill, isn't mechanics, and it isn't knowledge (I know this sounds dumb but hear me it), it is ego. People tell themselves "it is my teammates" or "I'm doing fine, it is just bad luck/trolls/afks", and sure those things are annoying and factors to a degree, but they aren't what holds most people back.
Everyone has an ego in this game whether they will fully admit it (Ego), and it is VERY hard to tell yourself you suck, or you are bad in x,y and z area, or that maybe it wasn't your teammates fault, it was your own. It took me a VERY long time to do that, because I wanted to believe I was good at the game, I wanted to believe someone else was holding me back, and in reality it was me and my ego, my unwillingness to learn from my mistakes because I wanted to believe I wasn't making many (which was horse crap).
It takes a while, but you have to know what your issues are first as well as your strengths, and go from there. Sure it may not be fast, hell you may reach Bronze 1 by the end of the season but that is okay...I promise. As long as you are going up, look at that positively. I may only be slowly going up from Silver 5, now in Silver 4, about to go up to Silver 3 (99lp sliver 4) and I hate that it is slow....but I'm improving, and I'm climbing.
There is no magic advice, no "play x champ/play x role/do x thing" because everything doesn't work for everyone. So while the advice someone, say in the YouTube videos you watch are sound, it might not be good advice for you specifically. Just take your time, and work on getting better, and worry about climbing second (honestly I don't even worry about my lp anymore. I purposely try not to look at it win or loss, and I feel so much better in ranked because of it).