Actually, connecting to single database is sufficient for me in most of the cases, so working without a schema would be great. How would I do this concretely? It did not find it in the documentation---apparently, working with a single database is (surprisingly) not very popular. Would I need to declare DB::Person as a subclass of ResultSource?
Take a look at DBIx::Class::DB. Even if you only want to connect to a single database only, it's strongly recommended to use a schema-based setup. Further explanations can be found in DBIx::Class::DB as well.
What's your reason against a schema, except you might never need all the features, which is not a problem in my eyes? Is it too much work to write "$schema->" all the time? I could understand that, but there are better ways around this than to use the connection-as-classdata style like Class::DBI does.