The Church does not teach the salvation of mankind in the sense that everyone is actually saved. When Christ died, it won universal redemption for all human beings, meaning that the gap between God and humanity that had been created by original sin was bridged and all people are potentially capable of salvation. Redemption happened corporatly which means it applies to all people without exception, and this is what Pope Francis was talking about. We are all children of God, all can do good, all are equally loved by God thanks to our resemption.
Salvation is individual, we could potentially all be saved, but not all of us actually are saved because some of us reject Gods offer of salvation. Our redemption was Gods loving act that made our salvation possible, and it gave the “power” or choice to us to accept or reject salvation. Think of it this way, we are all redeemed right now, we wont know if we individually are saved until death.
The only knowledge we have for sure of who is saved vs who isn’t is that the Saints are all saved for sure. The Church has also formally condemned universal salvation so we know for sure that not everyone is saved. Beyond that we do not know for sure who is and isnt saved.
What Pope Francis was re-iterating was the Churchs doctrine on redemption, he didnt say anything new. What he said is admittedly confusing if you dont know the difference between redemption and salvation.
When the Church speaks of the salvation of mankind it means it as a potentiality. God offers salvaion to all mankind, and wants us all to be saved, but not all of us ascent.