It looks to me like the lost world is who's being talked about. Especially considering everything else in the Bible.
There are those who are eternally dammed and those that are eternally saved and the scripture tells us about both.
Luke 19:10
for the Son of Man has come to seek and to save that which was
lost.”
Luke 21:18
But not a hair of your head shall be
lost.
John 6:12
So when they were filled, He said to His disciples, “Gather up the fragments that remain, so that nothing is
lost.”
John 17:12
While I was with them in the world, I kept them in Your name. Those whom You gave Me I have kept; and none of them is
lost except the son of perdition, that the Scripture might be fulfilled.
John 18:9
that the saying might be fulfilled which He spoke, “Of those whom You gave Me I have
lost none.”
Now, what do you think of Luke 15, Jesus gives us parables about that which was lost, consider them in light of these other verses about Christ saving that which was lost. Christ goes after His lost sheep. It is for them that He came to 'unlose' them. They are scattered abroad in God's field which is the world.
Christ comes to gather the lost sheep given to Him by God, they belong to the Great Shepherd as He owns them, but they are scattered abroad throughout the world, note v52 which mentions the lost sheep.
John 11:47-53New King James Version (NKJV)
47 Then the chief priests and the Pharisees gathered a council and said, “What shall we do? For this Man works many signs. 48 If we let Him alone like this, everyone will believe in Him, and the Romans will come and take away both our place and nation.”
49 And one of them, Caiaphas, being high priest that year, said to them, “You know nothing at all, 50 nor do you consider that it is expedient for us that one man should die for the people, and not that the whole nation should perish.” 51 Now this he did not say on his own
authority; but being high priest that year he prophesied that Jesus would die for the nation, 52 and not for that nation only, but also that He would gather together in one the children of God who were scattered abroad.
53 Then, from that day on, they plotted to put Him to death.
Apostle Peter tells us about the nation for whom He died. And about those who stumble over Christ the Rock, who were appointed or destined to stumble versus those who are a chosen people who obtain mercy, which means God extended mercy to them. So some are appointed to stumble over Christ and be damned as a result, and others to receive mercy from God and be saved.
1 Peter 2:7-10New King James Version (NKJV)
7 Therefore, to you who believe,
He is precious; but to those who are disobedient,
“The stone which the builders rejected
Has become the chief cornerstone,”
8 and
“A stone of stumbling
And a rock of offense.”
They stumble, being disobedient to the word, to which they also were appointed.
9 But you
are a chosen generation, a royal priesthood, a holy nation, His own special people, that you may proclaim the praises of Him who called you out of darkness into His marvelous light; 10 who once
were not a people but
are now the people of God, who had not obtained mercy but now have obtained mercy.