something I've recently noticed with characters -- mainly my d&d characters -- is that backstories are especially fun if you take a trope or a common backstory but change your character's role in it. Bonus points if they're the "villain" in this trope, whether by accident/misunderstanding or actions they intended to do but will/do regret after character development.
"my parents were killed by a (vampire/evil wizard/raging maniac/whatever)" but you're the one who killed someone's parents and now they're out to fucking Get You.
"my spouse/significant other died and I'm out to avenge them" but you're an undead or have the Reborn lineage or something and you're the dead spouse trying to find your revenge-obsessed lover before they do something they'll regret.
"my village was taken over by a tyrant" but you're the tyrant who's been chased out and fallen out of power and now you have to get Away From Here Fast.
"my noble family's manor burned down and I want to find the person who did it" but you're the housemaid who's been cast aside and put out of a job, and needs a quick way to make some money.
it sort of instantly gives the character more depth and makes the backstory feel more three-dimensional. Your character has done something wrong, whether by accident or on purpose, and that makes them feel more human. Not to mention the fact that many of these automatically create the easy-to-harness plot device of Someone Is After Me.
Anyways, hope that's helpful in some way :> happy character making!