If you have configured WinRM using the ConfigureRemotingForAnsible.ps1 script I would highly advise you to use HTTPS over port 5986 instead of HTTP. For one HTTP is sent over in cleartext and your credentials can be seen by anyone listening in. The other warning you are getting is because the cert validation variable is not correct, it should be ansible_winrm_server_cert_validation.
Change your inventory to be
ansible_user: ansibleadmin
ansible_password: Passw0rd
ansible_port: 5986
ansible_connection: winrm
ansible_winrm_transport: ntlm
ansible_winrm_server_cert_validation: ignore
Thanks
Jordan