Help me understand character backstory/motivation/hooks, because I'm very lost
Very disorganized mess of me trying to explain my perspective on the matter. Please bear with me.
When I first got into DnD, the group I started learning with had a style of "DM writes the story, players provide characters to experience the story with" which meant very little development of the characters was going to happen. It was basically a JRPG where you made a static character that would go through the DMs book, and I was fine with that. I'd never played before, how would I know anyone played it any differently? That first impression was my only impression of the game for about a year, and I think it's something I need to un-learn, but I also need to learn what the correct alternative mindset is, because my current one is definitely still wrong.
Over the years I've heard all kinds of horror stories about the extremes of "player's backstory is too long and act like the main character" and "player doesn't care about their own character and doesn't have a personality" so I try to stay in the middle where I care about my character but try not to be too intrusive.
I also hear stories about DMs that either butcher or completely ignore their players' backstories/goals, and have been in a few myself (I originally wrote them out, but this is the wrong sub for that) so avoiding that frustration is definitely another reason I avoid writing out long-term goals for my characters. Besides, if I really wanted my character to have a pre-determined set of experiences throughout the campaign, I'd write a book instead.
Most DMs I've played under try to convince me that my character needs a personal hook/goal within the campaign, and I just don't get it. The way I see it, we'll be going on whatever adventure the DM has planned anyways, why should my character's motivation for adventuring be something specific, and why should it be something different from whatever the main adventure is? If my character is only adventuring to get revenge or whatever, why would he go traveling with a bunch of strangers to do anything that isn't seeking that revenge? That's a distraction from my goal, and requires me to intentionally act against my character to join the adventure. So why even have a secondary goal if I need to pretend it's not that important in order for the game to even start?
That being said, if another player has a personal goal, I will do what I can to make that happen. The relationships and interactions between player-characters is my favorite part of the game, and helping them achieve their goals is part of that.