Literally never went to school or learned how to read or write.
You're describing every language for the overwhelming majority of the last 150,000+ years. English is not unique in that.
Which is why it’s one of the hardest languages to learn
It's not. English has a lot of irregularity to remember, but not the most. How difficult you find a language depends on your native language. English lacks things like elaborate case structures or grammatical gender which can be hard unless your native language has something similar. The 'th' sound is rare, but there are no clicks or tones. SVO is not the most common word order, but it's not the rarest.
there wasn’t even a noble population who were helping rules be set logically, it’s a slang language.
Huh? That's not how having a nobility works. Or what slang is. The rich aren't more logical, and they aren't concerned with making language easier. If anything nobles want more arcane language that takes longer to learn to better differentiate themselves from those with less free time.
It sounds like you're thinking of the prescriptive grammar movement where from the 1700s or so rich English speakers decided if it's not possible in Latin then it's uncouth in English, and started making up nonsense rules like no split infinitives or ending sentences with a preposition. They couched it in terms of being logical and correct but it was in reality a novel way of marking social class. And ~700 years after the English peasant/Norman aristocrat divide.