How Do You Navigate a Water Park in a Wheelchair?
If you can safely get out of your chair and to the slide, nobody is gonna stop you. The key to avoiding making people nervous is to move smoothly and consistently: your confidence will (mostly) become their confidence.
As for the other areas, you should be fine as long as you can easily transfer from your chair, even if that means just sticking your legs in the water for a splash.
If transferring is too difficult to do, I would suggest finding a comfortable spot, a cold drink and a good book. Take in the sun and white‐noise of the park and try to enjoy yourself in whatever way you think is best.