If you're gonna shoot playgrounds, then I think you need to suck it up and shoot with kids at them, creeped out parents or not (or make them not creeped out. Go to the trouble of asking and handing out legit business cards, etc., or go with a friend who has a kid and is willing to say you're their dad, etc. etc.).
If you absolutely can't abide creeping out parents or are convinced you can't change their minds and will get arrested then shoot something other than playgrounds? They are devices that exist for kids to play on them, so it is odd to not have kids. Unless you intentionally want it to be weird, like "oh look at my artsy sales brochure style" or go at midnight with a fog machine and make it a creepy abandoned zombie playground, well then have at it!
If you want to shoot playground equipment without kids, you can make your pictures interesting by going in close. There are quite a few geometric shapes there, and you could get a bunch of good pictures with creative framing of your shots.
What do you see in this equipment that makes you want to photograph it?
You don't have to tell me the answer to that question, but answering it for yourself will probably go a ways toward making better pictures of playground equipment. There are a bunch of possible reasons to shoot these things, all of which lead to different ways to handle them. What you have here are simple record shots, "here is this object", which doesn't give us any hint of what it is you're seeing there that's interesting.
No, these are far from awesome, of course. Just a quick heavy crop from your shots to probably give you some ideas to go back there and play with some close-ups on shapes, lines, geometry, angles and texture. As mentioned above the playground gives you an opportunity for some geometrical compositions, thats all. Actually it is a great training in finding balance, understanding visual weight, composition etc. I would probably go even closer by the way, but your images do not allow to crop too much here. Anyway, that's how I would try to shoot an empty playground.