What muggles know as gods today, were in fact just the most powerful wizards of the time. As time went on, many families who descended from them died out but a few descendants remain. Being a descendant of them is considered a great honor and extremely rare.
The wizarding world used to have Royals but that tradition was lost long ago. However, a prophecy was made by Cassandra Trelawney, that one day in 1981 the next heir to the royal throne would be born, a descendant of the 4 founders of hogwarts and of many royal families.
The prophecy:
When shadows cloak the Wizarding world, and hope is faint and slight,
A child shall be born, of ancient blood, on the eve of Samhain night.
Heir of founders four, purest lineage in her veins,
A royal throne awaits her, bound by destiny's chains.
With power deep and magic old, she holds the fate of all,
To unite or sever wizardkind, as darkness seeks to fall.
Born to face the greatest trials, with courage, heart, and might,
She shall stand against the storm, and bring the world to light.
Beware the serpents, wolves in masks, that seek to twist her path,
For only through her choice alone, will peace or wrath be cast.
In unity or shattered ties, her legacy shall write,
The dawn of a new era, or the endless night.Albus Dumbledore was the one who realised who the prophecy was about. Once Zellyana will go to Hogwarts, when she will go to the Headmaster's office she will meet Phineas Nigellus Black and Albus Dumbledore who will tell her about the Im prophecy. The minister (Kingsley Shacklebolt) has been made aware. The Supreme Mugwump Thadeus Dumbledore will be the one to arrange the coronation, where the ministers from over the world will come. The Royal outranks the Supreme Mugwump. Zellyana will be the firsy royal in 400 years. (After the curse is broken)
Phineas Nigellus Black
(Harry Potter Wiki)
He attended Hogwarts School of Witchcraft and Wizardry as a member of Slytherin House, later becoming the school's least popular Headmaster. He married Ursula Flint and together they had five children: Sirius, Phineas, Arcturus, Belvina and Cygnus. He banned Quidditch during the 1890–1891 school year,and did not participate in resisting Ranrok's goblin rebellion as most members of the staff did.
Following his death in 1925, his portraits were hung in the Headmaster's office to offer advice to the current Headmaster, as well as at 12 Grimmauld Place, the ancestral home of the House of Black which was used as the Order of the Phoenix headquarters. He was able to travel between both portraits, allowing him to play a contributing role during the Second Wizarding War.As an adult, Black became a professor at Hogwarts School of Witchcraft and Wizardry, a job which he loathed due to the impertinence of his students.He was later appointed as the Headmaster of Hogwarts by the British Ministry of Magic, accepting the position only for the prestige associated with it, and showing very little interest in acting as a role model or in children's education.While he was Headmaster, his two sons Sirius and Phineas both attended Hogwarts.