Because Jesus instituted a physical church which needs a leader…

I can’t tell if you’re trolling or genuinely curious. Joe Heshmeyer has done good work on early Christianity. He wrote the books Pope Peter and The Early Church Was the Catholic.

I think all Christians believe the Holy Spirit guides “the church,” even if they believe “the church” to be an informal community of believers. As the early Christians did, Catholics believe the Church is a physical presence on earth, which is to say, a real community with real leaders. Just like the apostles replaced Judas with Matthias, succession is essential to continue the mission of the Church.

Also, for the sake of clarity, papal infallibility is extremely narrowly defined. It exists because the (head of the) Church can’t officially teach error, which is a pretty obvious dogma if you already accept that the Holy Spirit is guiding it.