It is awkward to mention someone as a man/woman when you are saying hello or greeting. It sounds like Hello Man/Woman in English. You can say, Merhaba John/Kate or John Bey/Kate Hanım or Merhaba çocuklar/arkadaşlar. But most of the time just Merhaba is fine.

You can use Bey efendi / Hanım efendi instead of "man/woman".

Merhaba and Selam actually is arabic. But we also using common. Turkish hi,hello = Esenlikler (E-sen-lik-ler)

It literally translates as "Hello man/woman". Doesn't that sound strange to you even in English? You can say "Merhaba hanımefendi/beyefendi" which translates as: Hello madam/sir. You can also say "Merhaba Mariel hanım" or "Merhaba Jack bey" which translates into: Hello Ms. Mariel / Hello Mr. Jack.

Merhaba kelimesinde cinsiyet ayrımı yoktur hem adam hem kadın için kullanılır