How To Build Swing Set What Type Of Lumber Should I Use To Build A Backyard Swing Set/play House For My Kids?

What type of lumber should I use to build a backyard swing set/play house for my kids? - how to build swing set

I would rather just build a swing, two swings, a slide and a symbol for young children. I'm not crazy about using normal pressure-treated wood, because we are affected with arsenic.