The above lines show that you’re still having permission problems. This time on files in the data directory (/uar/local/var/mongodb/). My guess is that the files under this path are owned by the root user as well. To check run ls -alh /usr/local/var/mongodb/*. If things are owned by the root user, then you would either need to delete them or change the ownership of the files.
I’m assuming you installed via brew and then started the mongod as the root user and that’s why all the permissions are messed up. You should never run (almost) any service as the root user, and only then if you understand, and are willing to accept, the risks involved with doing so.