How do I turn off the OS-wide autocorrection and other forms of interpretive typing?

[Faize]

At random times, words are auto capitalized, and at other random times words are typed backwards, etc. How can I get rid of it all and have macOS output exactly what I press on the keyboard?

 

[zevrix]

At random times, words are auto capitalized, and at other random times words are typed backwards, etc. How can I get rid of it all and have macOS output exactly what I press on the keyboard?

Check you System Settings:

Keyboard > Input Sources > correct spelling etc.
Keyboard > Text Replacements

These settings are not system-wide though (even though Apple attempts to represent them as such), they only work in a small group of random apps.

You may also have some 3rd-party utilities that can affect this (TextExpander, Grammarly etc.)