The book starts with this guy's super-depressing life. He's abused and taken advantage of; it's him and his brother vs. the world. His brother is killed by a rich boy drunk driver who gets of scot-free and continues to be a pos; he kidnaps and kills him then commits suicide I think.
He is first reincarnated into the body of an recently dead alien in the middle of some high tech space battle, doesn't understand their language and they totally can tell he's not one of them, so his own alien species pretty much immediately murder him.
Can't remember if there was any more, but he then goes into the body of a baby that wasn't supposed to make it, starts cultivating from a super young age, finds a broken magic tower, goes to a magic school eventually, all while dealing with crippling mistrust of humanity and pretty much everyone he meets, which leads to him be very selfish, antisocial, violent, and murderous toward perceived enemies, etc.
He really starts some character development when he finds the tower, and later in school, when he meets people. It's a really rough road though.