Can Someone Explain The Lion King lore?

Hey guys, I’m sorry if this question has been asked a lot, but I’m watching The Lion King again, and I’m so confused about the storyline. I know there’s The Lion King, The Lion King II, and then you have The Lion Guard and, of course, the live-action movie and other stuff. Does Simba have one kid, two kids, or three kids? I’ve seen characters like Kion, Kopa, and, of course, his daughter Kiara, so I’m confused. Could someone please explain it to me? Also, I heard that they have books too. Did the books come out before the movie? I’m sorry if this sounds dumb, but how would that even work? And why didn’t the movies just follow the books? I’m just confused because correct me if I’m wrong but Simba is the main character of the whole franchise.