Is there a way to redirect users to the front page after they log in, without using any additional modules other than the core modules. Right now they are redirected to their profiles.
I don't believe it's possible to configure this in core, but there is a fairly well established and lightweight module that can do this for you - redirect_after_login - https://www.drupal.org/project/redirect_after_login
The query parameter
destination can be used to redirect any form submission, including the login form. Config your web server/Drupal to always add the query parameter such that http://example.com/user/login?destination=/ is the only URL to login. Upon login submission, users will be redirected to http://example.com/.