Go back a thousand years or so and you're equally related to an awful lot of people. Quite a lot of kings in that list, too many if you ask me. I think more realistically most of us are related to an obscure peasant somewhere in Eastern Europe.
There is an Irish king, Niall of the Nine Hostages 1500 years back whose DNA is carried by millions of people all over the world. He had a lot of kids apparently. Anywhere the Irish went but particularly prevalent in the North west of Ireland. Which as it happens is where my maternal Grandfather came from. So I may indeed be related to a King. But our family have trouble figuring out what happened to our paternal Grandfather who was a sailor and disappeared mysteriously sometime in the thirties. If we can't figure that one out, what chance do we have going back a thousand years?
On the other hand a legendry warrior who shares my surname was killed at the Battle of Clontarf way back in 1014! Given how few people have that name. There has to be a connection.