I’m 52. And in my entire adult life I’ve never made Jello. How about you?
The literal first comment in the thread mentions a confusion of the non-American vs American “world” in reference to naming.
The next highlights a difference in US English versus English elsewhere.
I’d long to hear how the context is solely US English.
How convenient to leave out the third comment, the one you replied to.
The second comment was not just “higlighting a difference in US English versus English elsewhere”, it was claiming that US English calls jam jelly, and the third one corrected that claim.
Of course there are other English speaking countries besides the US, but the third comment was absolutely justified in correcting what the second comment claimed. It’s not like there was some person from the US who said that all English is like that, making your comment pretty unnecessary.
