I started KCD back in 2019 but couldn't complete it. Honestly it didn't clicked me back in those days. But the story is quite grounded. A simple 5-10 mins of recap would suffice. (Official video is available)
The games also explains it, pay attention to initial conversations and after a point where you take control of your character. You'll understand all of it. I certainly did.
I say even if you haven't played the first one, you'll enjoy this. Blends well with older and newer audience. If you liked RDR2 then you'll definitely love this.