As said before, it's understandable Benjy would be as nostalgic about the past as he is, as it was the time the only really proof he was loved, Caddy, was present. He was called a "judgement" on his mother his whole life, his family seeing him as a bother rather than a blessing. Benjy's family, especially his mother, constantly worried about how Benjy would cause others to perceive the Compson family as a whole, causing a sort of resentment, shame towards Benjy. This also portrays the society of the South at that time, as everyone is fixated upon what others think of them. Benjy is barely a member of the Compson family, merely an obligation.
As there is a lack of consistency in Benjy's life, he strives for it. Sadly, Benjy lost one of the only consistent things in his life, Caddy. Caddy was who helped Benjy make sense of the world around him, now surrounded by only those who neglect him, he is lost. Benjy wants familiarity, maybe that's part of why he's so obsessed with all that's already happened. Benjy's extreme nostalgia shows the Compson family's clearly seen better days; presently, the family lacks order and happiness. The family and world around him is changing rapidly, and sadly, there's nothing Benjy can do to stop it.
Through the novel, Faulkner poses seemingly intended comparisons between Benjy and Jesus, possibly presenting Benjy as a Christ figure. This assumption can be based around Benjy's age being thirty three, the age of Jesus upon his crucifixion, his chapter taking placate day before Easter Sunday, as well as Benjy being the subject of abuse and suffering admit his innocence. It seems Benjy's comparison to Christ were intended to be presented to his audience, as he portrays Benjy as as the suffering underdog. Benjy's age being alluded back to Jesus sticks out because it's odd Faulkner would put such an emphasis on Benjy's age throughout the text. Like Jesus, Benjy is sort of just thrown into his suffering; Benjy has no power over his disability or the life he lives. And through this, Benjy, much like Christ, is subject to unnecessary abuse. Benjy can certainly reflect Christ's suffering, but among these similarities, there are also vast contrasts, meaning Faulkner could have made such allusions as a form of irony.