I had a very similar experience, watching it at Japanese camp when I was about 8. I had recurring dreams of a ship going down into a poison jungle for many years and vague memories of this movie.
I found it again when mail order Netflix first came out in my early 20s. It was like rediscovering my childhood and completing a character arc.
But I had remembered liking it. The glider, the giant bugs, etc.
I spent several years casually trying to find it. But “big ass bug anime” is kind of vague. Eventually I just started looking through catalogs of the timeframe from various distributors and studios.
I don’t know how or when, but eventually I was doing a deep dive on Miyazaki and Studio Ghibli and read the description of Naussica. Looked up screenshots. And there it was, that one bit from my childhood.