Wrong.
Time, not TimeLib
Adafruit SSD1306, not Adafruit_SSD1306
You are putting the wrong names in.
The warning you then get from the Time library is because… you did #include <Time.h> instead of #include <TimeLib.h> - time.h is a standard library included with the compiler, hence that name can’t be used for 3rd party libraries.
‘serial’ was not declared in this scope - C++ is case sensitive… where is the capital S?
Although you might have realised this by now, or not. It’s hard to tell with you jumping between threads, and then back to old versions of code. 