Mushoku Tensei: Jobless Reincarnation

Killed while saving a stranger from a traffic collision, a 34-year-old NEET is reincarnated into a world of magic as Rudeus Greyrat, a newborn baby. With knowledge, experience, and regrets from his previous life retained, Rudeus vows to lead a fulfilling life and not repeat his past mistakes. Now gifted with a tremendous amount of magical power as well as the mind of a grown adult, Rudeus is seen as a genius in the making by his new parents. (myanimelist)