I am no expert. But I do believe that theologians have explained that God wanted a creation to interact with that had free will. If Lucifer rebelled the way that most people think he did, it would lead you to believe that the Angels had free will as well, but I thought I had seen a verse that said that Angels didn't have the same
Very good young Padawan! Lucifer's rebellion is a troubling, sobering wake-up call for US not to take the Grace of G-d for granted.
Why did G-d create us? This would be one of those "great, existential questions." You know, the sort of thing the Bible was WRITTEN for! How 'bout this?
Rev 4:11 Thou art worthy, O Lord, to receive glory and honour and power: for thou hast created all things, and for thy pleasure they are and were created."
Kinda humbling, ain't it? I don't believe in "single verse theology," but that's an awfully good place to start, and impossible to argue with.
A deeper angle to look at is that with our every choice, we either serve and glorify satan, or the LORD. Literally every natural impulse we have is
against us glorifying the Lord, so for anyone at all to wind up on the right side of G-d's Throne of Judgment
really "speaks" to His Greatness.
And both these glimpses bring us to the VERY center of the Bible, which also happens to be the longest chapter, Psalm 119:
"Wherewithal shall a young man cleanse his way? by taking heed [thereto]
according to thy word."
Lord have Mercy, and help us to be ever mindful of this ...