The main superuser account is set up by initdb when run and will default to the current system user name, not postgres, unless an explicit -u/--username argument is given. From your above
\du output it's clear that when you set up the server you did it with your laygr system user as that user is the database server's main superuser account.
Should you mess up your login privileges or forget your password you can get back into the server if you have write access to it's data directory in order to be able to edit pg_hba.conf. Just change the auth-method on the relevant line to
trust and reload the server's config via
pg_ctl reload. You can then log in, fix your user/password, and then revert the changes you made to pg_hba.conf and reload the config again.