Who was the first ever lighthouse keeper?

Wood, most likely, followed by oils before electrification.

From Wikipedia:

The Lighthouse of Alexandria, also known as the Pharos of Alexandria (in Ancient Greek, ὁ Φάρος Ἀλεξανδρινóς), was a tower built between 280 and 247 BC on the island of Pharos at Alexandria, Egypt. Its purpose was to guide sailors into the harbour at night time.

Constructed from large blocks of light-coloured stone, the tower was made up of three stages: a lower square section with a central core, a middle octagonal section, and, at the top, a circular section. At its apex was positioned a mirror which reflected sunlight during the day; a fire was lit at night.

With a height variously estimated at somewhere in-between 393 and 450 ft (120 and 140 m), it was for many centuries among the tallest man made structures on Earth. It was one of the Seven Wonders of the Ancient World. ...