I don't know why they called it the Pav-a-lon (or "Pavalon"), except that half the other towns on the coast already had a Pavilion. Also, in earlier years, Huntington Beach really played up its crystal clear view of Catalina Island. The island even appears on the City's official seal. So perhaps Pavalon is a reference to "Avalon."
From our viewpoint, standing atop the drug store (later Jack's), we can see a tilt-a-whirl (always a favorite of mine), a carousel, and some sort of vomit-comet ride. There was also a small ferris wheel to the right of the carousel. I haven't been able to pin down just how long the mini-fun-zone lasted at this location.
Notice the banner announcing "Kid Ory's Creole Jazz Band" at the Pav-a-lon. Here's a YouTube clip from that very band, playing the "Muskrat Ramble" only a few years later.
For more about the Pav-a-lon, here's a link to a relevant article from the Independent by Jerry Person.