You've been given an explanation of a more complicated rule because, as you've stated previously, the more complicated rule confuses you even more.
Simply adding the clause "a prime number cannot be 1 / must also be greater than 1" would not have been confusing, and would have resolved the entire issue.

The stuff that is confusing to me is stuff like the "fundamental theorem of arithmetic", which is apparently something advanced enough such that I never heard about it in grade school and only heard about in this thread. I don't know why this "rule" exists, nor do I care. Regardless, since it never came up when I learned about prime numbers, it doesn't do much to combat the (apparently erroneous) idea that 1 might be a prime number.

When someone is explaining something and you don't get it, you should ask questions.
Again, there wasn't anything I "didn't get". To me back then, 1 being a prime number was just something that made sense, so there was no question to ask.

You can't ask a question you never had in the first place.

Don't pretend to be a victim of some bad educational system.
Don't tell me what I can't do.

Many people would agree the US education system sucks, anyway. Don't act like it's immune to criticism.