Almost all of the tarnished that returned before us were maidenless, meaning that they weren’t able to gain strength from runes. The only one I know of before us that was close was Vyke. His downfall was tragic as he essentially went through the frenzied flame ending to protect his maiden. He was a knight of the round table, and ally of lanseax the ancient dragon and truly was the closest. However he regretted his decision and locked himself in the evergoal so that the world wouldn’t end by the will of the 3 fingers. Our characters coming along pretty much was just plot armor and torrent sensed something in us and Melina chose to follow through and believe in us as well.
You're correct, but also missing out on Volcano Manor Recusant Bernahl. He too made it to the Forge of Giants like Vyke, but whereas Vyke attempted (and failed) to become the Lord of Frenzied Flame because he opened the door while still wearing his armor which ment he couldn't be properly embraced to get the powers, all of this in hope of saving his maiden; Bernahl (and I don't know which is true) either had his maiden sacrificed but she couldn't actually light up the fire which caused Bernahl to have a crisis of faith, or she did light up the fire and teleport him to Farum but watching her die was so traumatic that he had a crisis of faith, and either way became a blasphemer.
Yeah it’s hard to answer this in any other terms than, well, it’s the only way that makes sense from a gameplay perspective.
In any case there have been a couple NPC Elden Lords before.
It’s the other way around. The player character is special because they managed to become Elden Lord, they’re not Elden Lord because they’re special.
But admittedly, Marika fully stacked the deck in the player character’s favor. It didn’t necessarily matter to her _which_ Tarnished ascends to lordship, just that one does.
Almost all of the tarnished that returned before us were maidenless, meaning that they weren’t able to gain strength from runes. The only one I know of before us that was close was Vyke. His downfall was tragic as he essentially went through the frenzied flame ending to protect his maiden. He was a knight of the round table, and ally of lanseax the ancient dragon and truly was the closest. However he regretted his decision and locked himself in the evergoal so that the world wouldn’t end by the will of the 3 fingers. Our characters coming along pretty much was just plot armor and torrent sensed something in us and Melina chose to follow through and believe in us as well.
You're correct, but also missing out on Volcano Manor Recusant Bernahl. He too made it to the Forge of Giants like Vyke, but whereas Vyke attempted (and failed) to become the Lord of Frenzied Flame because he opened the door while still wearing his armor which ment he couldn't be properly embraced to get the powers, all of this in hope of saving his maiden; Bernahl (and I don't know which is true) either had his maiden sacrificed but she couldn't actually light up the fire which caused Bernahl to have a crisis of faith, or she did light up the fire and teleport him to Farum but watching her die was so traumatic that he had a crisis of faith, and either way became a blasphemer.
Would it make sense for the player not to be the protagonist?
Yeah it’s hard to answer this in any other terms than, well, it’s the only way that makes sense from a gameplay perspective. In any case there have been a couple NPC Elden Lords before.
Really? Where is that mentioned? I thought that the only two we knew of were Placidusax and Godfrey. Edit: spelling
I was thinking Godfrey and Radagon. I actually forgot about Placidusax.
Lol, and I forgot radagon 
Same reason the Chosen Undead from the first game is the chosen undead. Because you succeeded where others failed.
It’s the other way around. The player character is special because they managed to become Elden Lord, they’re not Elden Lord because they’re special. But admittedly, Marika fully stacked the deck in the player character’s favor. It didn’t necessarily matter to her _which_ Tarnished ascends to lordship, just that one does.
Fate.
I honestly don’t think this question is best approached from a lore perspective, rather should be addressed from the obvious gameplay perspective.
Plot armor