You would be hard pressed to find a better introduction to Shakespeare than Brendan Kelso’s Playing With Plays https://playingwithplays.com/. These short plays are not only designed to teach young kids about Shakespeare, they do so by allowing the kids to act them out!
Ian Doescher’s “Shakespeare Star Wars” is a must read for kids of all ages. Anyone who loves “Star Wars’ will love this series. This is how I got my son into Shakespeare
For the little ones, I recommend the move, “Gnomeo & Juliet. I don’t guarantee this will make a thespian out of your child, but it should make them giggle. There is poetry in a child’s laugh.
The Groundling's Guide to Shakespeare 