Private key generation method How was bitcoin private/public key created in 2009, I observed in the blockchain some bitcoin transaction took place early 2009 Feb - April.
In the original bitcoin core in github the first bitcoin core was released September 2009.
My confusion how were the users able to generate the address ?
Prior to BIP32, most wallets simply generated keys from random data provided by the operating system (or some other entropy source).

A handful of wallets implemented a brainwallet system, in which keys were derived from some kind of password, but they quickly fell out of use after it was discovered that most people selected easily guessable passwords which resulted in excessive loss of funds to theft.