The first error means that there are existing tables in the local H2 database (under standalone/data there are keycloak.* files).
It looks like the logic determined that they are of some previous db schema version, and tried to upgrade the schema to latest version, but unexpectedly the schema in place already seems to contain the tables it wasn't supposed to contain.
I suppose that could happen if upgrade process is interrupted by restarting the server?
Since you are using the default H2 database I assume you don't care about any existing data. The solution for you then is to stop the server, delete the database (rm standalone/data/keycloak.*), and start the server again.