I think that itch.io should implement some sort of rating system into the website. Here's a video discussing how this could work:
In case you don't want to watch the video, I'll give a summary.
Basically, itch could implement a checklist for developers to go through for each game, and the website would then rate the game based on this checklist. This would allow for ratings to be shown without a lot of pressure on the admins to rate every single game. To catch incorrectly rated games, there could be a way for users to flag a game, and after a certain game is reported enough, the website administrators could take a look. As a punishment for mis-rating your game, it could be taken down for a month. This will encourage developers to give their game a correct rating. Additionally, a message could be put on the game's page, explaining that the developer incorrectly rated their game. This will harm the developer more as it will turn users away from their products.
I think this system will help parents and users see what they are getting into before downloading a game. If you have any more ideas or changes to make, comment below. I hope you take this suggestion into consideration, and thank you for reading!