Using the moonlight affinity Artemis transferred to him, Jason was able to heal the Mewi, while additionally transferring a slight amount of mana without telling them.
This was extremely good and allowed him to tend to their injuries without going against their tradition and culture.
After he was done healing the few Mewi, he looked around using his Emperor Eyes, trying to see whether there were others who were in need of his help.
Fortunately, that was not the case, and he was able to leave the second Mewi village without further ado.
He disappeared as suddenly as he had emerged out of nowhere, making the Mewi believe that he was truly a ghost, or possibly even a holy spirit that had been sent to their rescue.
His aura and appearance were enough evidence to make them believe that the latter might be the case!