According to Catholicism, was Jesus a time traveller?
The simple answer is no.
Jesus Christ, the Second Person of the Blessed Trinity, in his human nature was truly Our Redeemer and brought us out of sin and into a life of sanctifying grace by his death on the Cross for our salvation.
There are no Catholic teachings that state Our Lord, while in his human nature was even remotely considered a time traveller, moving back and forth in time!
There nothing to imply that he was anything in his life that could compare to Doctor Who and his *or Black Adder with his time machine (Back & Forth).
Many Christians believe that Jesus is Christian is simply due to the Fact that Jesus was the Christ and died on the Cross for our salvation. Thus Jesus is to be considered the founder of all Christendom.
In fact the Followers of the Way were first called Christians and is even mentioned in Scriptures as such. The word Christian is used three times in the New Testament: Acts 11:26, Acts 26:28, and 1 Peter 4:16.
And when he (Barnabas) had found him (Saul or Paul of Tarsus), he brought him to Antioch. So it was that for a whole year they assembled with the church and taught a great many people.
And the disciples were first called Christians in Antioch. - (Acts 11:26)
Then Agrippa said unto Paul, Almost thou persuadest me to be a Christian. - (Acts 26:28)
Yet if any man suffer as a Christian, let him not be ashamed; but let him glorify God on this behalf. - (1 Peter 4:16)
If we considered Jesus to be the foundation of Christendom, I guess that would make him a Christian, but not a time traveller.