"Inheritance" means very different things to programmers and normal people. You can't expect domain use to follow your sensibilities.
¹ Let's leave for now what "class" means for programmers vs. other kinds of people.
The multiverse and other theories of multiple universes nominally belong to other fields of study.
Cosmology is the study of the universe we live in, specifically it’s development.
That’s why we have terms such as the local/near by universe and the observable universe. I find odd that none that that seem to take offense with the former mentions the latter, since grammatically they are identical.