I think you nailed it on the kids part. These are the kinds of activities that would be fun to do with my friends. These are not activities I would go do with people I barely know.

You need to make friends first and then invite them to these activities, not invite people to these activities as your way of making friends. Having kids that participate in the same thing is one of the easiest ways to make friends as an adult. Without kids, good luck. It's hard for anyone to make friends when you don't have a common activity holding you together until you can become friends. That's why people make friends in school and then struggle as adults. Lack of common activities. Volunteering or something like that were people can just show up and do things without knowing anyone else is probably your best bet.