Being open to the public is an invitation to check out the church. Churches are usually looking for new members all the time and looking for new ways to invite people to come on over. If someone thinks we are friendly and wants to come, great! If not, then hopefully we'll see them again sometime. The kid had fun getting his face painted, right? I go to Sunrise Service on Easter with friends but I stick with my own church week to week. I also took DD to a different church for an Easter Egg Hunt and while I'm sure that they do it in part to get out the word about who they are, it is a huge community event in a safe environment.
I went to all sorts of VBS programs as a kid. It was good for me to see how Mennonites and Baptists and Presbyterians weren't all that different from each other at the end of the day.
If you enjoy going, then keep going. If they ask you, tell them that you enjoy their activities and their company, but you have a home church you will continue to attend most of the time. That's what I tell the people on Easter Sunday. They don't mind that I'm there, and I appreciate the alternative worship opportunity. When I was a kid, I did Missionettes (which I think is something else now) at the local Assembly of God church. My church didn't offer the program. If my current church hadn't gotten some new kids, I was looking for a Sunday School for her because while I like my church, not all churches fill all needs.
It doesn't sound like they are forcing you to attend anything or volunteer for anything and it is enriching your overall experience. I'd keep going.