“Take what belongs to you and go. I choose to give to this last worker as I give to you. Am I not allowed to do what I choose with what belongs to me? Or do you begrudge my generosity?’ So the last will be first, and the first last.” Matthew 20:14-16
Eternal life is not fair; it is a gift of God’s grace. If eternal life were “fair” (that is, a payment to men, based upon the quality and quantity of their good works), no one would ever see heaven. Eternal life cannot be earned, but it can be received as a gift. That is what this parable was meant to convey.
It is not the “righteous” – that is, those who do the most good deeds – who get to heaven; it is sinners, who know that they deserve nothing but God’s wrath, but who gladly receive the gift of eternal life through Jesus Christ. It is not “the first” who get to heaven, but “the last” who get there, by grace through faith.