Both Matthew 18 and Luke 15 record Jesus’ parable about a shepherd who leaves 99 sheep in the fold to go in search of one that had wandered away.
Perhaps in this day & age, the metaphor above looses something in translation - so let's put it another way:
A father and his five children are asleep in their home when the smoke detectors go off. The father awakens to find his house filled with smoke and the sound of flames and crackling timber coming nearer. Panicked, he races to his children’s bedrooms and begins to rouse them. Calling to some and carrying others, he stumbles down the stairs and out the front door. He deposits the sleepy children on the grass a safe distance away and then turns. Gasping for air, he squints through the smoke to count kids: “Tim, Sally, Angel, Jojo—where’s Lilly!” He is missing his youngest, three-year-old Lilly. Four children are safe, one is not. What will this father do?
In these gospel passages and other parables, Jesus strives to get across the message that God loves & cares for every single person: individually - not just humanity in general. The Good News is that you are loved by God!