Okay kiddo, so the "protevangelium" is a big word that means "first gospel". It's a story that tells us about the very first time that God promised to send a savior to save us from our sins.
A long, long time ago, God made the world and all the creatures in it, including us humans. But one day, we made a bad choice and disobeyed God, which is called sin. Sin separates us from God and makes us sad.
But God loves us very much, and he didn't want us to be sad and separated from him forever. So even though we had sinned, he promised to send someone to save us and make things right again.
The protevangelium is the story of this promise. It says that one day, a great hero would be born who would defeat evil and make everything right again. This hero would be a special person chosen by God, and he would be born from a woman.
And do you know who that hero is, kiddo? He's Jesus! Jesus is the savior that God promised in the protevangelium. He came to earth to show us God's love and teach us how to live, and then he died and rose again to save us from our sins.
So the protevangelium is an important story because it tells us that no matter how much we mess up, God still loves us and wants to save us. And it reminds us that Jesus is the hero who has saved us and made things right again.