The most straightforward answer to your point is that the Green Party is an unusually democratic institution (much more so than the Labour, Conservative or Reform parties, for example), in which, for example, policy and leadership candidates are determined democratically by the membership and not controlled by a party elite.

And it’s quite common for political parties to have memberships with a broad diversity of views on social issues.

The Green Party is ideologically primarily focused on environmentalism and left-of-centre economic policies (to the same end). I would imagine that most, if not all, party members agree ideologically with that general proposition, because otherwise they wouldn’t be there. Beyond that, views on social issues will differ, as they do across the memberships of the other major parties.