Giving Chakra with sufficient Yang (for instance, Yang Release) has healing properties. Naruto's Chakra, or Kurama's Chakra, or a mixture of both, contain some of these properties; when he gives sufficient Chakra to a person, it can heal certain injuries, particularly minor ones (such as the injuries Kakashi suffered in Ch.609-610).
It wasn't until later, when Naruto obtained Hagoromo's Chakra, that he became able to provide extremely advanced healing to others (such as restoring Kakashi's eye, or stopping the after-effects of the Eighth Gate). In Kakashi's case, Naruto used "Creation of All Things" rather than simply sharing Chakra; in Guy's case, Naruto used high-level Yang Release.
However, Naruto was able to heal himself, Kakashi, and presumably Sasuke in Boruto, using only the properties of his Chakra. Naruto's Chakra is well known to contain incredible Life Force, particularly when he's also channeling Kurama's Chakra. Kurama's Chakra probably wouldn't have this property if Naruto weren't the one using it; when Kurama was a hostile entity, his Chakra acted like poison, creating wounds that stubbornly refused to heal.