It's a long shot that humans are Precursors. There is no proof that Precursors even ever existed they're part of a foreruner religion. Halo legends was made by 343 so it isn't offically part of the halo universe. Humans are reclaimers because they are the only ones that were supose to reclaim foreruner tech. Somewhere it said that foreruners pasted the mantle to humanity so humanity is a sort of heir to the foreruners. honestly I think that this theroy is a bit shaky