We Are Constantly Moving
At the same time came the disciples unto Jesus, saying, Who is the greatest in the kingdom of heaven? Matt 18:1
Agency And Opportunity Require "Fluidity"
Hierarchies are necessary, "If two things exist, and there be one above the other, there shall be greater things above them" (Abraham 3:18). Without them there is only chaos. But why is any hierarchy a spiritual principle? Interestingly, the word "hierarchy" means something like, "holy rule". Hierarchies can naturally form or can be forced. But in the gospel, they are created by "intelligence" or spirituality. Some times we want to submit to a hierarchy, other times we want to challenge or remove such authority. Priesthood is a form of hierarchy. Maybe the original form.
Jesus Christ offers us the best example of submitting and inserting Himself into the Fluid Hierarchy in a couple of ways. First, he fully submits to the will of our Heavenly Father and lowers Himself below the Father in the Hierarchy. Secondly, though He is who we worship, above us in the Fluid Hierarchy, He lowered Himself below all of us- "But he that is greatest among you shall be your servant." (Matthew 23:11) In other words, the Hierarchy is "fluid". Of course this applies to all of us as well.
Another way that the Fluid Hierarchy is "fluid", is that regardless of where we are in life with "intelligence" or our spirituality, through our choices we can move up or down that hierarchy. In other words, the Fluid Hierarchy is not rigid. Therefore, it does not matter where we find ourselves in the hierarchy, all that matters is that it is fluid and that we can progress through the eternities. This is in exact opposition to philosophies that would try to "flatten" the hierarchy of existing individuals, or to exclude those that don't fit into the hierarchy. Both of these approaches require tyranny.
A great example of this tyranny comes from the War in Heaven. It was Lucifer who wanted to flatten the hierarchy by removing or limiting agency and acting as tyrant- "Behold, here am I, send me, I will be thy son, and I will redeem all mankind, that one soul shall not be lost, and surely I will do it; wherefore give me thine honor." (Moses 4:1). Without agency there is no progress which eliminates not only the jierarchy but its fluidity. Additionally, the Fluid Hierarchy allows for everyone to move "up" eternally. that is, an eternal "increase" for everyone. One way to look at this is by family and genealogy. In a familial hierarchy your parents are always above you. But you also can become a parent filling the same role. This would add to both your increase and to your parents' increase moving both them and yourself up the Fluid Hierarchy. Therefore, all of you can have the same purpose, opportunity and growth even though you are below them in the hierarchy.
Another way to see this concept in the gospel is through the Parable of the Talents. It is important to understand that what was given to the servants are coins, not talents as we think of them today. In the parable, three different servants receive three different amounts of talents/coins. We won't address the "why" here, what is relevant is that the first two, the servant with five coins and the servant with two coins, both, with their opportunity, increase the number of coins while the third hides his away. The response from the Lord to the first two servants is the same, "Well done, thou good and faithful servant: thou hast been faithful over a few things, I will make thee ruler over many things: enter thou into the joy of thy lord." So it doesn't matter where we start or even where we find ourselves in the Fluid Hierarchy, and it certainly doesn't matter where someone else is in the hierarchy because we all have the ability of an eternal increase and "all that the Father has.". As President Oaks puts it, "The equality of God is not the equal outcomes for all, but equal opportunity for all."