I honestly don't mean this to sound nasty, but you need to brush up on your Bible study, history, and theology.
Jesus didn't start the Catholic Church. Jesus mentioned the Church only once (Matthew 16.18) as something He would do in the future. Under His headship, the Church was started by the Apostles under the power of the Holy Spirit (Acts 2). The Church that was started is called the Apostolic Church or the early Church. Only later in history does what we now call the Catholic Church evolve from the Church growing in the Roman Empire.
Some of the practices and traditions of the Catholic Church were started by Jesus, such as the Eucharist. But a lot of what Catholics teach (indulgences, theology of Mary, Purgatory, relics, papal infallibility, etc.) did not have its source in Jesus. These were added later by popes. Other practices, such as baptism, were also not started by Jesus. Jesus never baptized anyone, nor taught the necessity of baptism. Our understanding and practice of baptism came from the Apostles and the writings of Paul.
I'm a Protestant rather than a Catholic (both groups are Christians, by the way) because I think that Protestant teaching is biblical and that Catholic teaching is not. Some elements of Catholic theology that are not biblical:
- “Both Scripture and Tradition must be accepted and honored with equal sentiments of devotion and reverence.” (Catechism of the Catholic Church). In practicality, the Catholic Church sets herself above Scripture in rank of authority.
- Salvation by faith AND ALSO good works
- Eternal life is attained through Christ AND ALSO the sacraments
- The immaculate conception of Mary, her assumption into heaven, her role as co-redemptrix (believed only by some Catholics)
- Purgatory
- Veneration of relics
- Indulgences
- Invocation of the saints
- Infant baptism
- The infallibility of the papacy in their official, doctrinal statements
- The sacraments. Biblically, there are only two ordinances (baptism and the Lord's Supper), and they are ordinances, not sacraments.
- Magisterium
- The Mass as a sacrifice
- The truth and authority of the Apocrypha
- Extreme unction