Shiba Tatsuya reborn as Luffy with memories.

No magic but some of his healing capabilities can be kept and be explained either via Devil fruits or via Haki.

Can show him as highly intelligent and introspective as tries to research Haki and Devil Fruits.

His change in personality and desire for the title of King of Pirates can be attributed to to his dealing with full range of emotions first time in his life.

Maybe his Haki can be active from birth because he had Elemental Sight and Sixth Sense in his previous life so Observation Haki is already active. Rest he can learn later.