Add a simple string channel to your HTTP Thing, link to a test Item and see what the whole return is. Then you’ll know whether to blame JSONPATH.
Look in your openhab.log for relevant messages.
This is all I see in the log related to the http (accessed via port 9001)
2021-11-10 08:26:46.877 [INFO ] [nding.http.internal.HttpThingHandler] - Using the secure client for thing 'http:url:d6826c2660'.
2021-11-10 08:26:46.902 [INFO ] [nding.http.internal.HttpThingHandler] - Using the secure client for thing 'http:url:d6826c2660'.