Maybe https://m.wikidata.org/wiki/Wikidata:Main_Page is what you are looking for?

Yes! Thanks. In particular one might use "[is] instance of":

https://m.wikidata.org/wiki/Property:P31

So we would take in all items with that property to make the graph. Although we might have to deal with multiple roots.

There are also other interesting linking relations:

    Comparing items ...
    said to be the same as (P460)
    instance of (P31) - (is an example of ...)
    subclass of (P279) - (is a subset of ...)
    facet of (P1269) - (aspect of .../ subitem of .../ a broader perspective on the same topic is offered by ...)

    Item contains ...
    has part(s) (P527) - (contains ...)
    has part(s) of the class (P2670) (has parts that are instances of .../ some parts form subclass of ...)
    Example:

    Albert Einstein's brain (Q2464312) is part of (P361): Albert Einstein (Q937).
    Albert Einstein (Q937) is an instance of (P31): human (Q5).
    human (Q5) is a subclass of (P279): mammal (Q7377).
    mammal (Q7377) has part(s) (P527): mammary gland (Q189961).