Not sure you realize it, but your last paragraph is where the focus is in Judaism: doing good by one’s actions, being kind, giving charity, and treating others as we would like to be treated. Never once throughout my childhood and Jewish education was the afterlife mentioned at all in my family. It just wasn’t part of our Jewish life, although we were kosher, Shabbos observers, Hebrew School, and all the rest.
The ancient teachings of the Christian Church were often tangled up between the admonition that "faith without works is dead" and "salvation is by grace alone." But there was a strong belief in Heaven and Hell. In the same period covered by our New Testament, the Jewish Pharisees did believe in an afterlife while the Sadducees did not.
With those I've had any discussion about it my current Jewish friends and colleagues seem to be equally divided between those who do believe in an afterlife and those who do not or aren't sure. Some say they don't give it a lot of thought but focus on living here and now which isn't a bad choice in my opinion.
But believing in an afterlife, though I have no idea what it might be like, I am comforted and much less anxious about aging and time running out.
The Roman Catholic Church that evolved from the early Christian groups and dominated the Middle Ages taught then and to some extent even now that salvation was within the Church itself. If you are in good standing in the Church you are automatically heaven bound. The Priesthood had the power to forgive sins and set conditions for forgiveness and also the power to excommunicate a person from the Church which would consign that person to Hell. There were certain dictates and rules Catholics were expected/required.
In the 16th Century a German priest, Martin Luther, departed from RCC theology and returned to salvation by grace to the extreme, i.e. there was NOTHING a person could do to merit the grace of God and be admitted to Heaven but it was God's prerogative along.
And evolving out of that we have a gazillion different Christian denominations, some demanding strict adherence to rules and regulations, some allowing total liberty, and everything in between. Some believe they're the only ones who will go to Heaven, some believe only a relatively small number of people predestined to Heaven will get there, and others do not believe in Hell at all. And other religions have their own point of view about it all.
And in all that, I think those who love the Lord God and their neighbors may get some tweaking now and then, but I am pretty sure they will be okay.
