In my world, wood elves, of buried within a year in a grove, become a part of it (sorta like in Speaker for the Dead) and high elves choose to enact this ritual living separately.

These majestic trees grow to great heights, akin to redwoods. When such a tree dies of old age, the heartwood animates but has only the vaguest memory of its prior lives. That's the origin of warforged for my world. Incredibly rare, filled with history but oddly disconnected from it.

Haven't invented new races yet, only twists on existing ones.

Lizardfolk? Eat their dead with reverence, carve their stories onto their bones and then reanimate then for labor or battle. Their dead never truly die and remain a respected part of their culture.

Dwarves care about achieving immortality through craftsmanship, humans through magic. It's only halflings, and gnomes to a lesser extent, that have simply accepted death and lived their lives.