I am a PaRappa fan - the first game is good BUT the inputs are notoriously fucked up on that game. The timing is incredibly off, it’s not just you. One thing that helps is to freestyle and/or just not look at the timing that is presented on screen and just press buttons to the beat, which can be counterintuitive. They fixed it in PaRappa 2.

It was one of the first rhythm games ever made, so I’ll cut them some slack. The only way I am able to play it these days is because I have all the goofy timing and buttons memorized because I’ve been playing it for two decades