Hi Kat,
I am understanding this a bit different but I make no claim as to having the final word or ultimate understanding. This is what I am seeing, this parable (Prodigal Son) is actually addressing the Jews (first = older son) then Gentiles (second = younger son) but also as the "men of old" Prophets being raised to see those who came after them (the Elect) as being rewarded first into the Kingdom.
The Jews believe they have not strayed by following Mosaic Law under the First Covenant, the older son never strayed away from the (physical) duties he was given by his father but did he display or feel the (spiritual) love his father had for his younger brother, did the older brother truly appreciate all he was born into or did he feel as if he was somehow deserving of it? On the other hand the younger brother decided to go off on his own and through his journey of alienation and despair rediscovered how blessed he had been, then he repented for leaving "his first love," (his father) and the loving provisions his father had provided. When the younger son returned home he had a sense of humble appreciation that the older son could not fathom, who at this point loved (spiritual) his father more, the elder or the younger son? Who at this point would have more devotion?
When the Prophets are raised from the grave and discover the Kingdom is now populated by "only those who came after" them, what might be their reaction? Remember being under the Old Covenant they are raised still with a carnal nature. At Judgement they may be making the same statement as the the workers in the vineyard who worked from sunrise only to see the later workers not only paid the same but PAID FIRST! Might this be the beginning of the Elect having a hand in bringing the Prophets into the Kingdom? Where God is showing them they have more yet to understand, just as the older son now has less understanding and appreciation (than his younger brother) of the depth of his father's love, and the blessings he has provided?
Look at the preceding verses to what you posted;
Matthew 20
1For the kingdom of heaven is like unto a man that is an householder, which went out early in the morning to hire labourers into his vineyard.
2And when he had agreed with the labourers for a penny a day, he sent them into his vineyard.
3And he went out about the third hour, and saw others standing idle in the marketplace,
4And said unto them; Go ye also into the vineyard, and whatsoever is right I will give you. And they went their way.
5Again he went out about the sixth and ninth hour, and did likewise.
6And about the eleventh hour he went out, and found others standing idle, and saith unto them, Why stand ye here all the day idle?
7They say unto him, Because no man hath hired us. He saith unto them, Go ye also into the vineyard; and whatsoever is right, that shall ye receive.
8So when even was come, the lord of the vineyard saith unto his steward, Call the labourers, and give them their hire, beginning from the last unto the first.
9And when they came that were hired about the eleventh hour, they received every man a penny.
10But when the first came, they supposed that they should have received more; and they likewise received every man a penny.
11And when they had received it, they murmured against the goodman of the house,
I would bet the later workers did not murmur one syllable, they had a great appreciation for what they received, the sunrise to sunset workers got what they were promised (Old Covenant) but it was those who came later who got a better (New Covenant) promise.
Hebrews 8
5Who serve unto the example and shadow of heavenly things, as Moses was admonished of God when he was about to make the tabernacle: for, See, saith he, that thou make all things according to the pattern shewed to thee in the mount.
6But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises.
This has kind of veered off topic but you bring up an extremely interesting point which begs more study, I want to respond to some of the other posts here but time is not my friend at the moment.
Thanks to all who responded I will be getting back to this as soon as I can.
His Peace and Wisdom to you all,
Joe