Also, if we know, what were the first birthdays like? Were they only for royalty? Did people always give gifts for them? Any other interesting things about the history of birthdays?
From reading the Icelandic sagas, in medieval Iceland (and perhaps elsewhere in Scandinavia), people kept track of how old they were by how many winters they had lived through. The first day of summer was a feast day, with people exchanging small gifts. I'm not aware that people kept track of when they were born exactly, and I don't know when the practice of celebrating birthdays started. In modern Iceland, farm animals are still referred to by how many winters they have survived, but doing so for a person would seem incredibly archaic (comedically so).
hi! FYI, you may be interested in this section of the FAQ (link on sidebar)