Question

How was the first human being pair had done reproduction​

Answer 1

The origin of sexual reproduction in prokaryotes is around 2 billion years ago (Gya) when bacteria started exchanging genes via the processes of conjugation, transformation, and transduction[4]. In eukaryotes, it is thought to have arisen in the Last Common Eukaryotic Ancestor (LECA), possibly via several processes of varying success, and then to have persisted[5].

Since hypotheses for the origins of sex are difficult to verify experimentally (outside of evolutionary computation), most current work has focused on the maintenance of sexual reproduction. The maintenance of sexual reproduction in a highly competitive world had long been one of the major mysteries of biology given that asexual reproduction can reproduce by budding, fission, or spore formation not involving union of gametes, which reproduce at a much faster rate compared to sexual reproduction. 50% of offspring from sexual reproduction are males, unable to produce offspring themselves.

NOTE: NO HUMAN IS ENGAGED IN FIRST REPRODUCTION