The tree is supposed to be the first Jedi temple, I think. Or maybe the little village in general was the whole temple, but if I had to guess I'd assume it was the tree. Han mentions how those who knew Luke best thought he went to go find the first temple, and that's what the map in TFA leads to (the temple, not Luke). Which is also why the whole "We have the other part of the map recovered from the archives of the empire" line in TFA works. If it were a literal map to Luke, that wouldn't make sense.
Anywayyyyy - I'm pretty sure the tree is the actual "temple" of the first Jedi, that might be confirmed in the book I don't remember. I'm not sure if it's explicitly stated anywhere if Luke found the books there or if he brought them, but I think the intention is that they were there. He definitely didn't make the books. When Yoda burns the tree and Luke is like, dude you just burnt the sacred texts! The "read them have you? page turners, they were not" line implies Luke didn't write them. I also believe that them being ancient and some of the first jedi texts is in the visual dictionary, I just can't recall if it is stated that they were on the island or not initially. I would also be interested to know that if anyone can chime in haha