Ansible uses wrong SSH user

Running Ansible commands on Hosts does not work because Ansible uses the wrong user. Running SSH commands works fine. (setting the ansible_user parameter does nothing)

Expected outcome:
Ansible should use the same user as SSH or have an option to select the correct user.

Foreman and Proxy versions:

Other relevant data:

Error initializing command: Net::SSH::AuthenticationFailed - Authentication failed for user root@
Exit status: EXCEPTION