“The two adult women he was traveling with on the slide also suffered injuries. One suffered a broken jaw, and the other a broken bone in her face and had to have stitches in her eye, according to the local news station.”
Noticed that in the article at your link. Sounds like the kid struck them on the way up & out of the raft.
Good golly.
My theory is the two women sitting at the back weighing over 200 lbs each caused the nose of the raft to hydroplane and lift enough to catch the boy's head in the safety netting above.