It seems that you are relying on your private interpretation of these passages to accept infallibility. There is no mention of infallibility in this passage. The Apostles are sent to teach and baptize. That is no guarantee that those they teach, such as any successors, would not teach error.
Based on this line of reasoning, since the term “infallibility” is not specifically mentioned in Scripture, it does not exist. And, then for that matter, since the term, “Trinity” is not mentioned, it does not exist either.

False teachers were a problem with the early church - just like today.
Jesus says He will be with them always. Again this does not mention infallibility.
You would have us think that while Christ will be always with us - He will allow His Church (and, that would be the Catholic Church) to teach error - to deviate from His Own Word? Does that make any sense?
Does this mean that where two or three people have gathered in His name that they cannot teach error because He is with them?
Obviously, this is an area of ‘private interpretation’ because with 20,000+ groups, assemblies, houses, bodies, and cults all claiming to follow Christ - and most with at least 3 members - but all teaching contradictory doctrine - this can not be what this passage means.
The promise to be with them does not apply to just the Apostles. Jesus will be with all believers.
So, you would have us believe that - even by your own understanding - Christ established His Chruch on the faith of Peter (as opposed to Peter, himself) yet when Peter died (and of course his faith died with him) that it ended there? Here we have Paul, commissioning both Timothy and Titus to carry on his work as an Apostle - making both of these men successors to the Apostles. And you obviously dispute this?
Again, there is nothing here that suggests ongoing infallibility. The Holy Spirit will guide the Apostles into all truth. It says nothing about successors nor does it guarantee that error will not be added to the truth by others later.
Finally, the essence of the argument. You are content with the ‘private interpretation’ condemned by Peter but claim that Church established by Christ was a one-generational event. With the death of St. John in 100AD - you are saying that Christ just turned His Church lose? While Christ could have chosen to do anything to effect our salvation - He chose to die on the cross. That is a lot of work for one generation - and everyone thereafter is not subject to the false teachers that would wreck havoc on the flock. To go along with your view, one would have to believe that being an ‘orphan’ (just what Christ told us that He would not leave us) is what we now have.
There has been so much debate on the meaning of this passage that I am surprised that you would put it forward as one that speaks for itself.
The issue with SS, at least as I interpret is that it is, very simpy, a tradition of man. It is a tradition that originated in the 16th Century and was devised specifically to replace the Catholic Church’s teaching authority with anything else. You will recall that it was the Catholic Church that gave the world the Canon.
With respect to the gates of the netherworld, gates are really a defensive measure, not offensive. They are meant to keep something out or something in. Here Jesus is saying is that the Church, through the spreading of the Gospel will set free those held captive by death. It doesn’t say anything about infallibility.
Just who do you think is attacking the Devil? Honest, SyCarl, the Devil is the one attacking every human soul in an effort to bring about their eternal damnation. So, while you may like to think that the Devil is hunkered down behind his gates in a defensive posture, the reality is quite different. David tells us he is a roaring lion seeking whom he may devour - that is no kitten cowering int he corner he is talking about.
Yes the Church is the pillar and foundation of the truth. However it is not the truth itself. God’s word is truth. This passage does not guarantee infallibility as pillars and foundations can crumble.
You apparently are limited God’s Word to the written word? Actually, since we did not have all of the Books that would become the Bible even in existence until 60AD when the first NT Bood was written and 100AD - when the last was penned - we have to wonder what those very early Christians did when it came to believe in Christ - with no Bible in print. And, since the Canon was not established until 400AD - what provided the Word of God to these Christians? It was Sacred Tradition - the oral instruction Paul identifies in addition to his writings - that was the very foundation of the Church.
You are also assuming that when Scripture refers to the Church that it means and is restricted to the Catholic Church as an institution. That is not something I accept.
And, that is your responsibility.