Good Luck at the Beginning, Reborn as a Little Taoist Priest

[Single male protagonist + system + time travel + ancient history + omnipotence] The single male protagonist accidentally encounters "great luck" and travels back to the Hongwu period of the Ming Dynasty. The original owner was an orphan who relied on his master since childhood and practiced Taoist methods since childhood. Accidentally obtained a system called "Treasure Bag", medical skills? Saving people? And you said your name is Zhu Laosi? Then who is your father? Your name is Xu Da? Do you know Xu Da? Why can I get any door and a time machine?? What is your name? Li Er???? Is it so fantasy??