The Symbol may actually be about transition.
I am rewatching the first episode and I have seen a theory online that the town draws in people at “cross-roads” or in transition. I noticed that as the Matthews drive into town, there are various shots and transitions of roads before they see the tree.
The roads loop like the From Symbol, and Tabitha and Jim even argue about looping in a circle and about a “switch back” road that could get them on the right path, then they see FromVille and drive around before almost crashing into Jade and Tobey. I think once you turn back from the tree, the trap is set. The Tree could be a Faraway tree.
It is almost as if the Ocean would be a way out. I also noticed that the Monster’s mouth parts look like fish teeth and that their internal structures resemble those of trees.