Then he wasn’t truly human like us
So he was baptized with his own spirit he already had?
Jesus' begotten soul unified with His body makes Him fully human. His Holy Spirit unified with His soul makes Him fully God.
The Holy Spirit in Jesus was functioning in two ways, as His life source - "As the Father has life in Himself, so He has given to the Son to have life in Himself" John 5:26, ( to have life in oneself is a quality only God can have and which gave Jesus the ability to rise from the dead); and as the Holy Spirit that a man would receive so Jesus could function as the first spirit-filled man.
It's important to understand that the Three are all abut salvation. The life in the blood of Jesus, which is the Holy Spirit of eternal life is released to the believer through Jesus. That is why He breathed the Holy Spirit into His disciples after His resurrection.