St. Catherine of Siena was running around in the middle of the Renaissance. And she was an ordinary laywoman, pushing ordinary laypeople to know God better and do more good, as well as telling the Pope to do his darned job and get back to Rome, and giving all sorts of advice letters to kings and queens, princes and princesses.
There were bad people who were buying their way to becoming priests, and foolish people who were taking church offices without doing it to serve Christ. St. Catherine spent a lot of time telling those people how deadly of sins they were committing. But at the same time there was all the simony and sinning, it was also a time of revival of Catholicism, especially among laypeople.
The Renaissance was also the time when there were whole towns and villages in Italy that were run as lay religious communities (“communes” is what the history books say, but it’s nothing like the hippies – it’s more like having your local church clubs become the government, and the Knights of Columbus becoming the local army). Cities like Siena tried all sorts of different governments, including various forms of republic and democracy. There was a lot going on.
It’s okay to tell kids a little bit about both sides. It’s good for kids to know that when things look dark and people are doing bad things, God calls His people to live the right way, and sends saints to help them do it.