Satan or The Devil never fell from a position of Grace or Perfect Beauty.

He has always been evil from the beginning.

Jesus Christ said in John 8 vs 44

You belong to your father, the devil, and you want to carry out your father’s desires. He was a murderer from the beginning, not holding to the truth, for there is no truth in him. When he lies, he speaks his native language, for he is a liar and the father of lies.

Notice the - He was a murderer from the beginning line meaning he has always been evil from the start

Isaiah 14:12-17 was talking about King Nebuchadnezzar not an evil entity or a divine being.

Lucifer is a Latin word that means “light bearer” and was originally the name for the planet Venus, known as the “morning star.”

Note that Prior to 1611 , Lucifer never appeared anywhere in scripture....

Isaiah 14 vs 16 simply says this entity is a man.

"Those who see you will gaze at you,
And consider you, saying:
‘Is this the man who made the earth tremble,
Who shook kingdoms"

Is Satan a man?