There are a few things I might try to help make the game easier and possibly more enjoyable for a young player in vanilla. Use commands to "keep inventory on death" and turn off temporal storms while they are playing. You could travel far south where there are no wolves and the bears don't attack on sight then use the command to teleport her character when she joins the world. Fence off an area and place lights through out, then set her spawn in that area with a gear so she has a safe space to venture from on lower rift nights if she wants. This way she can decide how much fighting she wants to do. If she likes it and gets better, then as suggested you could give her armor and head out together. If not, then this game has lots to offer. Many hours can be spent on activities such as decorating, cooking, and animal husbandry. They all can be done in that safe fenced off space. And there is nothing better than creating a base together. And this way she can always command you to go down into the scary mines to get such and such.