This is what David would have looked like - brown skin, blackish/brownish hair - like every other Semite
he was definitely not north European looking
There is a reason, a purpose, why that word ‘ruddy’ was specifically attributed to David. Then follow by the reminder in Revelation to the ‘key of David’. The image you present does not look anything like what words were used to describe ‘young’ David.
The Key of David as in Rev 3:7 "The words of the holy one, the true one who has the key of David, who opens and no one shall shut, who shuts and no one opens." is Jesus - Jesus is pictured as the one who holds the "key of David" which is earlier referred to as "the keys of Death and hades" (Rev 1:18). This "key of David" is mentioned in Is 22:22 where Eliakim replaces Shebna as the leading minister of David's kingdom.
In Isaiah the "key" of the kingdom is a symbol of the authority of David given to the minister/steward who acts with the authority of the king. "He shall open and none shall shut; he shall shut, and none shall open"
Jesus makes further reference to this when HE calls himself "the one who opens and no one shall shut, who shuts and no one opens."
Jesus holds the Key as He is the King in the line of David.
As we see, Jesus as the King, gives this authority to Peter, making Peter the steward/prime minister of God's Kingdom I will give you the keys of the kingdom of heaven, and whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven" Mt 16:19 -- Peter is the steward of the authority of Jesus, God who is the true holder of the Keys as we read in Rev 3:7
This is what David would have looked like - brown skin, blackish/brownish hair - like every other Semite
he was definitely not north European looking
Actually the Old Testament wasn’t “fixed” - there were differences between the Septuagint and the Babylonian in terms of the minor prophets. Everyone agreed with the Pentateuch, but which of the minor prophets and other books were to be added was left until the council fo Jamnia in 70 AD that defined Jewish canon
21 “Then if anyone says to you, ‘Look, here is the Christ!’ or, ‘Look, He is there!’ do not believe it. 22 For false christs and false prophets will rise and show signs and wonders to deceive, if possible, even the [g]elect. 23 But take heed; see, I have told you all things beforehand.1 Cor 11 talks about the admonitions to the Israelites in the past as warnings for the future
And let's be clear - Revelation 22:18-19 talks about "this book" namely the Book of the Revelation of St. John --> don't you realize that the Bible is made up of 73 books ending with the book of the Apocalypse?